Peanut nitrogen credits to winter wheat are negligible under conservation tillage management in the southeastern USA

Field Crops Research 249 (2020) 107739

Contents lists available at ScienceDirect

Field Crops Research journal homepage: www.elsevier.com/locate/fcr

Peanut nitrogen credits to winter wheat are negligible under conservation tillage management in the southeastern USA

T

Arun D. Jania,*, Michael J. Mulvaneyb, John E. Ericksonc, Ramon G. Leond, C. Wesley Woode, Diane L. Rowlandc, Heather A. Enloef a

University of Florida, Horticultural Sciences Department, Indian River Research and Education Center, 2199 South Rock Road, Fort Pierce, FL 34945, United States University of Florida, Agronomy Department, West Florida Research and Education Center, 5988 Hwy. 90, Milton, FL 32583, United States c University of Florida, Agronomy Department, 3105 McCarty Hall B, Gainesville, FL 32611, Unites States d North Carolina State University, Department of Crop and Soil Sciences, 4402C Williams Hall, Raleigh, NC 27695, United States e University of Florida, Soil and Water Sciences Department, West Florida Research and Education Center, 5988 Hwy. 90, Milton, FL 32583, United States f University of Florida, Soil and Water Sciences Department, 2181 McCarty Hall A, Gainesville, FL 32611, Unites States b

A R T I C LE I N FO

A B S T R A C T

Keywords: Peanut (Arachis hypogaea L.) Winter wheat (Triticum aestivum L.) Nitrogen credits Conservation tillage

Agricultural extension services in many peanut (Arachis hypogaea L.)-producing regions recommend that farmers reduce nitrogen (N) fertilization rates, or apply N credits, to crops planted after peanut but do not typically specify how peanut residue management or planting schedules of subsequent crops affect the magnitude of peanut N credits. The objective of this study was to quantify peanut N credits to winter wheat (Triticum aestivum L.) in a conservation tillage cropping system in different subtropical growing environments. A five site-year study was conducted in Florida, USA beginning in 2016. A split-plot experimental design was arranged in which summer crop [peanut, cotton (Gossypium hirsutum L.), and weed-free fallow] was the main plot factor, while N rate (0, 34, 67, and 101 kg N ha−1) to winter wheat was the split plot factor. Peanut and cotton were planted under strip-tillage, while winter wheat was drilled into peanut and cotton residues and weed-free fallow plots without tillage. Although peanut residues accumulated 54–93 kg N ha−1, plant available N at winter wheat planting in the 0–15 cm soil depth range of former peanut plots was only higher than in former cotton or fallow plots for one site-year. A previous peanut crop did not affect winter wheat grain yield, but there were cases of lower grain yield, grain N removal, and agronomic efficiency following cotton relative to peanut depending on site. Nonlinear regression procedures predicted that N rates required to optimize grain yields following peanut would exceed 94 kg N ha−1, further indicating the absence of detectible peanut N credits in this study. These results suggest that assuming peanut provides N credits to subsequent crops in the southeastern USA is not justified and, if assumed, will reduce the productivity of subsequent crops.

1. Introduction In addition to being a lucrative cash crop, peanut (Arachis hypogaea L.) is often credited with augmenting soil nitrogen (N) pools by engaging in biological N fixation. Throughout the southeastern USA, Cooperative Extension Services recommend that producers assume a 22−67 kg ha−1 N credit to crops planted after peanut (Caddel et al., 2012; Buntin et al., 2007; Crozier et al., 2010; Maguire and Heckendorn, 2011; Wright et al., 2011; VDCR, 2014). Nitrogen credits in this context refer to the N fertilizer replacement value of a previous legume to a subsequent crop (Bundy et al., 1993; Ennin and Clegg, 2001). There is currently a lack of information regarding the impact that planting schedules of subsequent crops and peanut residue ⁎

management practices have on the size of peanut N credits. Nitrogen mineralization from peanut residues is best characterized by an initial rapid phase of N mineralization followed by a gradual and longerlasting phase, during which less total N is mineralized (Yano et al., 1994; Thippayarugs et al., 2008; Hemwong et al., 2009; Mulvaney et al., 2017). Previous studies have shown that peanut residues incorporated after harvest mineralize N more rapidly than residues retained on the soil surface (Mulvaney et al., 2017; Jani et al., 2019). Given the importance of time and residue placement on N availability following peanut harvest, there are likely large differences in the size of peanut N credits to subsequent fall- and spring-sown crops. Environmental conditions in many subtropical regions where peanut is grown are not conducive to long-term retention of available N

Corresponding author. E-mail address: ajani@ufl.edu (A.D. Jani).

https://doi.org/10.1016/j.fcr.2020.107739 Received 30 August 2019; Received in revised form 6 December 2019; Accepted 29 January 2020 0378-4290/ © 2020 Elsevier B.V. All rights reserved.

Field Crops Research 249 (2020) 107739

A.D. Jani, et al.

in soil. Frequent and intense rainfall events on coarse-textured soils in the southeastern USA can lead to substantial NO3-N leaching (ReyesCabrera et al., 2017a, 2017b). Considering that spring planting occurs several months after peanut is harvested, a substantial portion of N mineralized from peanut residues would likely no longer be available for spring-sown crops. Litterbag studies conducted throughout the region have shown that peanut residue loads ranging from 3500 to 6700 kg ha−1 can mineralize 1–18 kg N ha−1 during cotton (Gossypium hirsutum L.) sown the following spring (Mulvaney et al., 2017; Jani et al., 2019). Such modest estimates of N mineralization likely explain results from previous studies in the southeastern USA that showed maize (Zea mays L.) grain and seed cotton yields did not respond to rotations with peanut under both conventional and conservation tillage (Meso et al., 2007; Jordan et al., 2008). Although peanut N credits to spring-sown crops are apparently negligible, the short time interval between peanut harvest and planting fall-sown crops, in addition to rapid N mineralization rates from peanut residues following harvest, suggest that winter cereal productivity can be enhanced by N supplied by a previous peanut crop. Earlier studies have estimated that 15–41 kg N ha−1 can mineralize from peanut residues during a subsequent winter wheat (Triticum aestivum L.) crop, depending on residue load size (Mulvaney et al., 2017; Jani et al., 2019). Those studies revealed that N mineralization rates would be fastest within 30 days after planting (DAP) winter wheat, with the amount of N mineralized likely to be sufficient in meeting basal N requirements of winter cereals (Weisz, 2013; Noland et al., 2018). Sustained higher N availability following peanut harvest may explain improvements in winter wheat productivity following peanut compared to other summer crops observed in many tropical and subtropical regions (Searle et al., 1981; Yano et al., 1994; Sharma and Behera, 2009). In the southeastern USA, there has been limited research focused on the responsiveness of winter cereal cash crops to a previous peanut crop. Earlier studies have focused primarily on winter cereal biomass accumulation and have produced mixed results. Zhao et al. (2010) reported that oat (Avena sativa L.) biomass accumulation in Florida was higher following peanut than cotton for one of two years, while Balkcom et al. (2007) found that rye (Secale cereale L.) biomass accumulation was not affected by retention or removal of peanut residues in Alabama. Additional research is needed to better understand winter cereal grain yield response to a previous peanut crop. Such research should consider different growing environments and include an N fertilizer-free summer fallow component in the treatment structure to enable accurate estimates of peanut N credits to winter cereal cash crops. Considering the low fertility status of many peanut-producing soils throughout the world, priority should be given to evaluating peanut N credits under conservation tillage practices that aim to improve longterm soil fertility. Conservation tillage has been used successfully in a broad array of subtropical cropping systems to improve soil physical properties and enhance soil organic C and N pools (Sainju et al., 2002; Hubbard et al., 2013; Larsen et al., 2014). Studies have also shown that peanut can be highly productive when planted into crop residues under strip-tillage (Jordan et al., 2008; Balkcom et al., 2010), suggesting that peanut N credits to winter cereal cash crops are potentially large under conservation tillage management. The objective of this study was to quantify peanut N credits to a winter wheat cash crop under conservation tillage management in different subtropical growing environments. We hypothesized that peanut would provide detectible N credits to winter wheat, the magnitude of which would be proportional to peanut residue N content.

Table 1 Initial soil properties from 0−30 cm soil depth at both study sites. Nutrients were extracted from soils using Mehlich-3 reagent. 2016-17

2017-18

2018-19

Soil properties Texture

Units –

Citra Sand

Jay Sandy loam

Citra Sand

Jay Sandy loam

Jay Sandy loam

Organic matter pH CEC

g kg−1 – meq 100 g−1 mg kg−1 mg kg−1 mg kg−1 mg kg−1 mg kg−1 mg kg−1 mg kg−1 mg kg−1 mg kg−1 mg kg−1

5.1 6.9 3.6

23.7 5.9 8.8

5.4 6.7 3.1

13.6 6.2 7.3

NDa 6.4 6.8

139 20 49 462 7 0.5 1.5 5 151 0.5

25 82 90 950 49 0.3 1.9 15 24 0.5

49 26 33 372 3 1.0 1.1 2 11 0.4

97 144 105 778 11 0.3 5.1 128 88 1.7

41 266 158 1190 5 0.5 6.2 19 13 0.8

P K Mg Ca S B Zn Mn Fe Cu a

No data available.

and Education Unit in Citra, Florida (29°24’31’’N, 82°08’49’’W, 19.2 m elevation, 0–5 % slope) and the West Florida Research and Education Center in Jay, Florida (30°46’32’’N, 87°08’14’’W, 62.5 m elevation, 0–2 % slope) during 2016-17, 2017-18, and 2018-19 (Jay only). The study took place on a Candler sand (hyperthermic, uncoated Lamellic Quartzipsamment) and Red Bay fine sandy loam (fine-loamy, siliceous, thermic Rhodic Kandiudult) in Citra and Jay, respectively. Weather data during the study were collected from stations operated by the Florida Automated Weather Network at each location. Sites were selected based on their different climatic and soil characteristics. Citra has historically had warmer winter temperatures than Jay in addition to having less fertile soil (i.e. lower organic matter content and cation exchange capacity). Prior to beginning the experiment each year, soil was collected to 30 cm depth using a 2.54 cm diameter soil probe. Samples were collected in a ‘W’ pattern throughout the field, homogenized manually, and bulked. A subsample was drawn and evaluated for several soil properties (Table 1). Mehlich-3 reagent was used to extract nutrients from soils. The experimental design was a randomized complete block (r = 4) with a split-plot restriction on randomization, where levels of summer crop (peanut, cotton, and fallow) were randomized to main plot units, and N rate (0, 34, 67, and 101 kg N ha−1) to a subsequent winter wheat crop to subplot units. Winter wheat plots receiving 0, 34, 67, and 101 kg N ha-1 are referred to herein as 0 N, 34 N, 67 N, and 101 N plots, respectively. A maximum rate of 101 kg N ha-1 was selected because University of Florida Cooperative Extension Services recommend this rate to optimize grain yields (Wright et al., 2016b). Main and subplots were 14.6 m by 7.6 m and 3.7 m by 7.6 m, respectively. Although peanut N credits were of primary concern in this study, cotton was included in the treatment structure because it is commonly rotated with peanut in many subtropical cropping systems and evaluating winter wheat performance after both crops could better inform N management decisions for winter wheat. Fallow plots were not fertilized during peanut and cotton cycles. 2.2. Summer crop management Field preparation began in spring with strip tillage in zones approximately 30 cm wide and 40 cm deep. Peanut (cultivar Georgia06 G) and cotton (cultivar PHY 333) were planted at rates of 175,000 and 142,000 seed ha−1, respectively, in rows spaced 91 cm apart. All major field activities are presented in Table 2. Fertilization and irrigation practices were based on yield goals of 4.5 and 2.5 Mg ha-1 for

2. Materials and methods 2.1. Field site and experimental design A five site-year study was conducted at the Plant Science Research 2

Field Crops Research 249 (2020) 107739

A.D. Jani, et al.

Table 2 Major field activities at study sites. Experimental year

Site

Activity

Dates

2016-17

Citra

Peanut and cotton planting Peanut and cotton harvest Soil sampling for inorganic N Wheat planting N topdress application Wheat harvest Peanut and cotton planting Peanut and cotton harvest Soil sampling for inorganic N Wheat planting N topdress application Wheat harvesta Peanut and cotton planting Peanut and cotton harvestb Soil sampling for inorganic N Wheat planting N topdress application Wheat harvest Peanut and cotton planting Peanut and cotton harvest Soil sampling for inorganic N Wheat planting N topdress application Wheat harvest Peanut and cotton planting Peanut and cotton harvest Soil sampling for inorganic N Wheat planting N topdress application Wheat harvest

17 May 2016 4 October (peanut) and 6 October (cotton) 2016 3 November 2016 4 November 2016 30 January 2017 31 May 2017 18 May 2016 4 October (peanut) and 10 October (cotton) 2016 1 December 2016 2 December 2016 31 January 2017 ND 4 May 2017 27 September 2017 (peanut) 7 November 2017 8 November 2017 24 January 2018 10 May 2018 26 May 2017 20 October (peanut) and 18 November (cotton) 2017 17 November 2017 18 November 2017 19 January 2018 15 May 2018 18 May 2018 2 October (peanut) and 8 October (cotton) 2018 28 November 2018 29 November 2018 29 January 2019 20 May 2019

Jay

2017-18

Citra

Jay

2018-19

Jay

analysis

analysis

analysis

analysis

analysis

a Wheat grain yield data were not available for the 2016-17 experimental year at the Jay site because excess soil moisture during the harvest period prevented access to the field. When field access became possible, the crop had lodged. b A Hurricane during the 2017-18 experimental year at the Citra site stripped cotton bolls from plants and harvest data could not be collected.

peanut pods and cotton seed, respectively. Cotton received 101 kg N ha−1, while peanut did not receive N fertilizer. Timing and methods used to apply all inputs were based on best management practices (BMPs) recommended by University of Florida/Institute of Food and Agricultural Sciences Extension Services (Wright et al., 2016a, 2017). Within one day of planting peanut and cotton, glyphosate (Makaze®, Loveland Products, Loveland, CO) was applied to main plots at a rate of 0.92 kg a.i. ha−1, while S-metolachlor (Dual Magnum®, Syngenta Crop Protection, Greensboro, NC) and pendimethalin (Prowl®, BASF Corporation, Research Triangle Park, NC) were applied at rates of 1.26 and 0.87 kg a.i. ha−1, respectively, for weed control. Fallow plots received three additional applications of glyphosate from June through September to minimize weed biomass accumulation as weed biomass would be a potential source of N for the subsequent winter wheat crop. For in-season weed control in peanut plots, a single application of 4(2,4-dichlorophenoxy) butyric acid (Butyrac® 200, Albaugh, LLC, Ankeny, IA) and imazapic (Cadre®, BASF Corporation, Research Triangle Park, NC) was made one month after planting at rates of 0.44 and 0.07 kg a.i. ha−1 respectively. Weed growth was controlled in cotton plots during the season with one additional application of glyphosate applied at the previous rate. Fungicides were applied to both peanut and cotton on a scheduled basis. Chlorothalonil (Bravo Weather Stik®, Syngenta Corporation, Basel, Switzerland), pydiflumetofen (Miravis®, Syngenta Corporation, Basel, Switzerland), and flutolanil (Convoy®, Nichino America, Wilmington, DE) were applied in rotation to peanut at rates of 1.09, 0.05, and 0.70 kg a.i. ha−1, respectively. Fluxapyroxad and pyraclostrobin (Priaxor®, BASF Corporation, Research Triangle Park, NC) were applied to cotton at a rate of 0.18 kg a.i. ha-1 within one to three weeks after first bloom. Within one day of harvest, peanut and cotton aboveground biomass (minus reproductive components) was collected using a 0.25 m2

quadrat. Three subsamples from representative areas of each main plot were collected and reproductive components removed. Biomass subsamples within each main plot were bulked and dried to a constant weight at 60 °C. Peanut pod and seed cotton yields were estimated by combine harvesting main plots. Cotton was not harvested in Citra 201718 due to hurricane damage. Following cotton harvest, stalks were mowed down and left on the soil surface. Peanut pod yields were reported on a moisture basis of 100 g kg−1. The peanut combine was not equipped with a residue spreader, so residues were distributed manually within two days after harvest.

2.3. Soil sampling for available nitrogen analysis Soil cores were collected from peanut, cotton and fallow main plots using a tractor-mounted hydraulic probe (Giddings Machine Company, Windsor, CO) one day before winter wheat planting. The probe (5.7 cm diameter, 1.5 m length) penetrated soil to 1 m in depth at four representative locations of each main plot. Cores were partitioned in 0–15, 15–30, 30–60, and 60–100 cm intervals, composited into one sample by depth for each main plot, and dried at room temperature. One additional core was taken per block to estimate bulk density at each depth interval. Bulk densities from the four blocks were averaged by depth interval, resulting in values of 1.08, 1.09, 1.1, and 1.1 g cm−3 for 0–15, 15–30, 30–60, and 60−100 cm intervals, respectively. Available N (kg ha-1) was calculated at each depth interval using each respective bulk density. In 2017, the hydraulic probe could not be used in Jay due to excessive soil moisture below 15 cm in depth. Instead, a handheld soil probe (2.54 cm diameter) was used to collect soil samples at the 0−15 cm depth interval. In each main plot, eight representative samples were collected, mixed, and composited. In 2018, the handheld soil probe was used again in Jay due to excessive subsoil moisture in Jay, but sample collection to 30 cm in soil depth was possible. 3

Field Crops Research 249 (2020) 107739

A.D. Jani, et al.

Fig. 1. Daily maximum (dashed lines), minimum (dotted lines), and mean (solid lines) air temperatures (C) at 2 m above the soil surface and precipitation (mm, bars). Data were collected from on-site weather stations managed by the Florida Automated Weather Network (FAWN).

4

Field Crops Research 249 (2020) 107739

A.D. Jani, et al.

2.6. Weather conditions

Table 3 Peanut and cotton yields, residue and residue nitrogen accumulation, and residue carbon and nitrogen concentration and ratio (C/N) for all site-years. Year

Site

Crop

Yielda

Residues kg ha−1

2016-17

Citra

Peanut Cotton Peanut Cotton Peanut Cotton Peanut Cotton Peanut Cotton

783 882 3609 1680 4142 ND 6583 2838 6125 3255

2860a 2160a 3500a 4160a 3700a 1689b 4350b 5623a 4792a 4442a

Jay 2017-18

Citra Jay

2018-19

Jay

b

N

C g kg−1

N

C/N

64a 35a 54a 56a 80a 30b 81a 75a 93a 60a

377.4a 358.4a 351.4b 403.8a 374.2a 381.3a 386.7a 405.2a 399.2a 403.9a

22.5a 16.2b 15.5a 13.4a 21.7a 18.0a 18.5a 13.3a 19.4a 13.5a

16.7b 22.1a 22.7a 30.1a 17.2a 21.2a 20.9b 30.5a 20.6a 29.9a

Atmospheric temperatures were generally higher in Citra than in Jay during the study. Temperature differences between sites were most pronounced during the winter wheat growing period (Fig. 1). Average monthly temperatures were 1−4 °C higher in Citra compared to Jay from November through February. There were also fewer freeze events in Citra than in Jay. During winter wheat production in Citra 2016-17, average monthly temperatures from December through February exceeded the 15-year average by approximately 5 °C. Total rainfall in Citra 2016-17 was 91 % lower than in 2017-18, and 36 % below the 15year average (data not shown). In Jay, total rainfall approximated the 15-year average in all site-years, but untimely distribution (approximately 702 mm in May-June 2017) prevented winter wheat harvest in Jay 2016-17 as previously noted.

a

Yield data refer to peanut pods (10 % moisture) and seed cotton. Peanut yields were substantially reduced by sandhill cranes (Grus canadensis) in Citra 2016-17, while a hurricane in Citra 2017-18 stripped cotton bolls from plants. b Means within the same column and separated by site-year that have the same letter are not significantly different at α = 0.05 according to ANOVA Ftest.

2.7. Laboratory analyses Peanut and cotton biomass were ground to pass a 1 mm sieve (Thomas Wiley Laboratory Mill, Thomas Scientific, Swedesboro, NJ) and then ball milled using the Mixer Mill MM 400 (Retsch, Newton, PA). For cotton, only leaves and thin branches (< 10 mm diameter) were ground because the mill was not designed to process woody materials. Following ball milling, samples were analyzed for C and N concentration using a CHNS analyzer by the Dumas dry combustion method (Vario Micro Cube; Elementar, Hanau, Germany). Winter wheat grain samples were ball milled and analyzed for total N using the same method. Biomass C and N content were determined by multiplying the percent C and N of biomass by biomass dry weight. Nitrogen removal with harvest was determined by multiplying grain yield by grain N percentage. Soil samples were analyzed for available N concentration using the microplate method developed by Sims et al. (1995). The process began with grinding air-dried soil samples to pass a 2 mm sieve. After sieving, 5 g of soil from each soil sample were extracted with 25 mL of 2 M KCl and shaken for 1 h. After shaking, samples were allowed to settle for 30 min before filtering. Extracts were stored at 4 °C until analysis with a SpectraMax® 250 microplate reader (Molecular Devices, San Jose, CA) set to a wavelength of 650 nm. Devarda’s alloy was used to reduce nitrate (NO3−) to ammonium (NH4+), while indophenol blue was the chromophore employed to assess available N concentrations. Samples were run in duplicates and compared against prepared standards at R2 > 0.99.

2.4. Winter wheat management Winter wheat was planted at a rate of 111 kg ha−1 in rows spaced 19 cm apart using a no-till grain drill. In 2016-17 site-years, the cultivar Baldwin was used but was replaced by cultivar AGS3000 in subsequent site-years due to high incidence of leaf rust (caused by Puccinia recondita) and uneven flowering by Baldwin at both sites. Fertilization (except for N) and liming were based on soil test reports. For plots receiving N fertilizer, urea (46-0-0) was used with 25 % of N applied at planting and 75 % topdressed at Feekes 5 growth stage (Large, 1954). Supplemental irrigation amounted to approximately 300 and 21 mm in Citra and Jay, respectively, for each year and was applied based on University of Florida/Institute of Food and Agricultural Sciences Extension Service recommendations (Wright et al., 2016b). Within one day of planting, glyphosate was applied at a rate of 0.92 kg a.i. ha−1 for weed control. Approximately one month after planting, mesosulfuron-methyl (Osprey®, Bayer CropScience, Research Triangle Park, NC) was applied for additional weed control at a rate of 0.01 kg a.i. ha-1. Pyraclostrobin (Headline®, BASF Corporation, Research Triangle Park, NC), tebuconazole (Monsoon®, Loveland Products, Loveland, CO), and fluxapyroxad (Priaxor®, BASF Corporation, Research Triangle Park, NC) were applied in rotation at rates of 0.15, 0.16, and 0.06 kg a.i. ha-1, respectively, for fungal disease control.

2.8. Data analyses Analysis of variance (ANOVA) was conducted using nlme, lsmeans, lme4, and car packages of R statistical software version 3.4.1 (R Development Core Team, 2012) to assess response variables. Initial analyses indicated interactions between year with treatments for most response variables. Therefore, site-years were analyzed separately. Summer crop and N rate were treated as fixed effects, while replication and interactions between replication and main effects were treated as random effects. Pairwise comparisons for all response variables were made using Tukey’s honest significant difference (HSD; α = 0.05). Winter wheat biomass, grain yield, and grain N removal data were fit to linear and quadratic models using the lm () command in R 3.4.1. Model selection was based on adjusted R2 values.

2.5. Winter wheat data collection Aboveground biomass was collected from winter wheat plots within two days of harvest using a 0.25 m2 quadrat. Samples were taken from two representative areas per plot and dried to a constant weight at 60 °C. Winter wheat was combine harvested from the central 1.3 m portion of plots, and yields were determined on a 120 g kg−1 moisture basis. Grain weights obtained from biomass samples were added to plot yields. In Jay 2016-17, excessive soil moisture delayed field access during the harvest period. When the field became accessible, the crop had already lodged and could not be harvested for that site-year. Grain yields were used to determine agronomic efficiency (AE), defined as Δ grain yield per kg N fertilizer applied (Cassman et al., 1996). Although only N fertilizer was considered when determining AE, any differences in AE as a function of summer crop would provide insight into summer crop N contributions to winter wheat.

3. Results 3.1. Summer crop performance Peanut and cotton met yield expectations at both sites with a few notable exceptions. In Citra 2016-17, sandhill cranes (Grus canadensis) fed extensively on immature peanut pods, drastically reducing yields 5

Field Crops Research 249 (2020) 107739

A.D. Jani, et al.

Fig. 2. Available N (kg ha−1) at winter wheat planting in former peanut, cotton, and fallow plots at depth intervals of 0–15, 15–30, 30–60, 60–100, and 0−100 cm. Excess subsoil moisture prior to planting winter wheat limited sampling to 0–15 and 0−30 cm depths in Jay 2017-18 and Jay 2018-19, respectively. Error bars represent standard errors of the mean. Bars that share the same letter separated by site-year are not significantly different at α = 0.05 according to Tukey’s HSD. Note: Available N at 0−100 cm depth was not compared to other depth intervals within a siteyear because it was determined simply by adding N levels at the other depths.

3.2. Available nitrogen at winter wheat planting

(Table 3). However, peanut residue accumulation that site-year was sufficiently large (2860 kg ha−1) to suggest overall crop performance was adequate to test for peanut N credits to winter wheat. Although cotton was not harvested in Citra 2017-18 because of hurricane damage, cotton residue accumulation was congruent with expectations for the site, allowing evaluation of winter wheat performance following cotton that site-year. Peanut and cotton residues contained similar amounts of N in four out of five site-years (Table 3), the lone exception occurring in Citra 2017-18 when peanut residues contained 55 kg N ha−1 more than cotton residues. Peanut and cotton residues had similar C/N ratios in three site-years, while C/N ratios were 25–30% lower in peanut residues relative to cotton residues in two site-years.

The effects of summer crop and soil depth on N availability at winter wheat planting depended on site-year. In Citra 2016-17 and 2017-18, there was some indication of greater N availability at lower soil depths compared to shallow depths, but results were inconsistent (Fig. 2). Additionally, only a modest amount of available N was detected at lower soil depths in Citra, ranging from 16 to 24 kg N ha−1 in the 60–100 cm soil depth range. Within a given soil depth range, summer crop usually did not affect N availability at either site. There was only one site-year in which peanut enhanced N availability. In Jay 2016-17, former peanut plots had a larger amount of available N (37 kg N ha-1) in the 0–15 cm soil depth range than former cotton (16 kg N ha-1) or 6

Field Crops Research 249 (2020) 107739

A.D. Jani, et al.

Fig. 3. Winter wheat stover accumulation in response to fertilization with 0, 34, 67, and 101 kg N ha−1 in former peanut, cotton, and fallow plots. Error bars represent standard errors of the mean. Note: Excessive soil moisture prevented stover from being collected in Jay 2016-17.

ha−1 less than grain harvested from 0 N former peanut plots in Jay 2017-18 (Fig. 5). However, grain yields following peanut and fallow were similar at all N rates, indicating no peanut N credit was present that site-year. There were no other cases where summer crop affected grain yield, or the amount of N exported with harvest in other siteyears. Grain yield response to N rate resembled stover accumulation response but was detected in all site-years. The quadratic model generally provided a stronger fit to grain yield data than the linear model and was used to estimate the N rate required to maximize grain yields. For Citra site-years, the optimal N rate ranged from 80 to 105 kg N ha−1 and was not affected by summer crop (Table 4). The quadratic model predicted grain yields in Jay site-years would respond to N rates surpassing 120 kg N ha−1. Pairwise comparisons between optimal N rates based on summer crop were not possible in Jay because optimal N rates often exceeded the N rate scale that was used (Table 4). However, the fact that optimal N rates following peanut exceeded 110 kg N ha-1 in Jay further indicated the absence of detectible peanut N credits in this study. Agronomic efficiency was primarily driven by N rate and depended on site-year. Averaged over summer crop, highest AE was achieved in 67 N plots in Citra, where values amounted to 4 and 11 kg kg−1 in Citra 2016-17 and 2017-18, respectively (Fig. 6). A different trend was observed in Jay 2017-18, where AE decreased as N rate increased. Averaged over summer crop, AE decreased by 8 kg kg-1 moving from 34 N to 101 N plots that site-year. The only case of a summer crop effect on AE was observed in Jay 2018-19. Averaged over N rate, AE was lower in former cotton plots (1 kg kg−1) than in former peanut (14 kg kg−1) or

fallow (22 kg N ha-1) plots at winter wheat planting. Total available N from 0 to 100 cm soil depth was also higher following peanut compared to cotton that site-year. 3.3. Winter wheat performance In three out of four site-years, winter wheat stover accumulation was driven primarily by N rate (Fig. 3). Averaging over summer crop, stover accumulation peaked in 67 N plots for both Citra site-years and in 101 N plots in Jay 2017-18. However, there was no relationship between stover accumulation and N rate in Jay 2018-19. In all cases where there was a positive relationship between stover accumulation and N rate, the largest stover responses were detected at the lowest N rates. Depending on site-year, there was a two- to six-fold increase in stover accumulation moving from 0 to 34 N plots. The only case where summer crop affected stover accumulation occurred in 34 N plots in Jay 2017-18 in which former cotton plots accumulated 1000 kg ha−1 less stover than former fallow plots. The quadratic model best described stover accumulation as a function of N rate, revealing that large amounts of N (≥ 83 kg N ha−1) would be required to optimize stover accumulation (Table 4). In three out of four site-years, the model estimated N rates exceeding 120 kg N ha-1 would be needed for optimal stover accumulation following peanut (Fig. 3), suggesting peanut N credits to winter wheat were negligible. As with stover accumulation, summer crop had only a limited effect on grain yield. In Jay 2017-18, grain yields were lower following cotton compared to peanut or fallow in 0 and 34 N plots (Fig. 4). Grain harvested from 0 N plots previously planted to cotton also exported 16 kg N 7

Field Crops Research 249 (2020) 107739

A.D. Jani, et al.

Table 4 Parameters from models used to characterize winter wheat stover accumulation, grain yield, and grain N removal in response to different N rates (0, 34, 67, and 101 kg N ha−1) and summer crops (peanut, cotton, and fallow). Nopt refers to the N rate required, as predicted by the model, to achieve highest stover accumulation, grain yield, and grain N removal. Parameter Stover

Year

Site

2016-17

Citra

2017-18

Citra

Jay

Grain yield

2018-19

Jay

2016-17

Citra

2017-18

Citra

Jay

Grain N

2018-19

Jay

2016-17

Citra

2017-18

Citra

Jay

2018-19

Jay

Summer crop Peanut Cotton Fallow Peanut Cotton Fallow Peanut Cotton Fallow Peanut Cotton Fallow Peanut Cotton Fallow Peanut Cotton Fallow Peanut Cotton Fallow Peanut Cotton Fallow Peanut Cotton Fallow Peanut Cotton Fallow Peanut Cotton Fallow Peanut Cotton Fallow

Equation 2

f = 90.79 + 18.05x - 0.06x f = 43.88 + 17.02x - 0.08x2 f = 19.02 + 14.24x - 0.07x2 f = 547.66 + 37.10x - 0.13x2 f = 400.21 + 43.82x - 0.20x2 f = 285.45 + 52.98x - 0.29x2 f = 1628.87 + 37.89x - 0.10x2 f = 1136.18 + 35.30x - 0.08x2 f = 1878.87 + 39.24x - 0.17x2 f = 2309.24 + 20.93x - 0.14x2 f = 2540.85 - 6.6x + 0.09x2 f = 2125.00 - 5.9x + 0.09x2 f = 28.64 + 4.37x - 0.02x2 f = 20.55 + 4.83x - 0.03x2 f = 1.46 + 4.01x - 0.02x2 f = 157.6 + 19.11x - 0.10x2 f = 140.02 + 16.25x - 0.08x2 f = 198.09 + 12.23x - 0.06x2 f = 1795.56 + 32.09x - 0.12x2 f = 755.32 + 35.35x - 0.10x2 f = 1316.74 + 44.07x - 0.21x2 f = 2002.31 + 17.98x - 0.08x2 f = 2035.31 + 6.23x f = 1328.83 + 23.16x - 0.07x2 f = 0.59 + 0.08x - 0.0003x2 f = 0.43 + 0.11x - 0.0007x2 f = 0.05 + 0.08x - 0.0005x2 f = 3.44 + 0.46x - 0.003x2 f = 2.31 + 0.41x - 0.003x2 f = 5.20 + 0.26x - 0.001x2 f = 31.41 + 0.42x - 0.0002x2 f = 12.51 + 0.52x - 0.0007x2 f = 24.30 + 0.70x - 0.003x2 f = 35.79 + 0.48x - 0.003x2 f = 38.79 + 0.11x f = 25.06 + 0.45x - 0.001x2

Nopt (kg ha−1)a

R2adj.

P > F

> 120 103 104 > 120 108 93 > 120 > 120 117 83 > 120 > 120 105a 80a 100a 95a 102a 100a > 120 > 120 105 110 > 120 > 120 > 120 77 94 87a 79a 93a > 120 > 120 > 120 64 > 120 > 120

0.99 0.81 0.86 0.99 0.99 0.99 0.94 0.96 0.98 0.49 0.95 0.10 0.94 0.42 0.76 0.72 0.73 0.79 0.97 0.97 0.99 0.82 0.34 0.99 0.90 0.48 0.73 0.69 0.63 0.61 0.97 0.98 0.99 0.92 0.14 0.99

0.03 0.24 0.21 < 0.001 < 0.001 0.03 0.13 0.10 0.07 0.41 0.12 0.54 0.14 0.44 0.29 0.31 0.30 0.26 0.10 0.11 0.04 0.24 0.25 0.03 0.18 0.41 0.29 0.32 0.35 0.36 0.08 0.06 0.04 0.16 0.35 0.04

Means within the same column and separated by parameter and site-year that have the same letter are not significantly different at α = 0.05 according to Tukey's honest significant difference test. In several cases, pairwise comparisons were not possible because either Nopt exceeded the highest N rate (101 kg N ha−1) or a linear equation best described data.

fallow (19 kg kg−1) plots, which were statistically similar (data not shown).

from peanut residues prior to planting winter wheat. However, plots formerly planted to peanut only had larger amounts of available N than former cotton or fallow plots at winter wheat planting for one site-year, providing further evidence that peanut residue-derived N is often retained in soil for only a short period and should not be relied upon as an N source for subsequent crops. Rainfall patterns during the period between peanut and cotton harvest and winter wheat planting in addition to lack of available N accumulation at lower soil depths suggest leaching was not a major pathway of N loss at either site. Rainfall amounted to 20–61 mm in three out of four site-years during this period and was fairly evenly distributed. Previous research conducted at the Jay site revealed that NO3-N leaching was negligible (∼ 1.3 kg N ha−1) even at high fertilization rates (150 kg N ha−1) in the absence of intense rainfall events within 60 DAP for several different crop species (Reyes-Cabrera et al., 2017b). Given that available N at 30–60 and 60–100 cm depth intervals was not affected by summer crop during any site-year, there were likely pathways other than leaching that were largely responsible for low N availability at winter wheat planting. Ammonia (NH3) volatilization is not often considered to be a major pathway of N loss from leguminous residues but may partially explain findings in this study. Previous research has shown that NH3 located within 1.0 cm of the soil surface at air temperatures above 20 °C can volatilize rapidly (Overrein and Moe, 1967; Sommer et al., 1991). In a laboratory incubation, Janzen and McGinn (1991) found that volatilization from leguminous residues placed on the soil surface was

4. Discussion There was no evidence to support our hypothesis that peanut would provide detectible N credits to winter wheat, the size of which would be proportional to peanut residue N content. Although peanut residues contained larger amounts of N than what has previously been reported for peanut in the southeastern USA (Balkcom et al., 2004; Meso et al., 2007), peanut residue C/N ratios were sufficiently low to facilitate rapid N mineralization (Mulvaney et al., 2010; Vahdat et al., 2011; Sievers and Cook, 2018) and possibly loss under local environmental conditions. Cherr et al. (2006) found that leguminous residues containing up to 120 kg N ha−1 at the Citra site did not affect subsequent sweet corn yields, underscoring the short residence time of available N under environmental conditions in the southeastern USA. Harvest and planting schedules in the southeastern USA result in gap periods between peanut harvest and winter wheat planting. In this study, winter wheat was planted one- to two-months after harvesting peanut, during which time a substantial portion of N was likely mineralized from peanut residues. Mulvaney et al. (2017) modeled N mineralization from surface-applied peanut residues in the region in early October at N loading rates (48–71 kg N ha−1) that approximated the range found in our study (55–81 kg N ha−1). Applying that model to our data showed that 25–37 kg N ha-1 would potentially mineralize 8

Field Crops Research 249 (2020) 107739

A.D. Jani, et al.

Fig. 4. Winter wheat grain yield response to fertilization with 0, 34, 67, and 101 kg N ha−1 in former peanut, cotton, and fallow plots. Error bars represent standard errors of the mean. Note: Vertical axis scales are different. Excessive soil moisture prevented grain harvest in Jay 2016-17.

characterized by a rapid flush during the first week followed by an extended period of minimal volatilization. In our study, peanut residues were retained on the soil surface at air temperatures ranging from 21 to 24 °C during the initial 30 days after harvest, which would be conducive to volatilization. Glasener and Palm (1995) reported that volatilization accounted for 8 % of N losses from peanut leaves during a 21-day laboratory incubation, but greater losses are conceivable under field conditions. Considering Larsson et al. (1998) determined that 17 % of mineralized N from alfalfa (Medicago sativa L.) residues was lost due to volatilization within 30 days under field conditions in temperate Sweden, it is reasonable to expect greater N losses from peanut residues by volatilization in the subtropical southeastern USA. While peanut had minimal impact on soil N availability at winter wheat planting, there was some indication that cotton may have reduced N availability to winter wheat in Jay. Nitrogen partitioning to cotton residues was relatively high in Jay, falling within the range of values previously reported in the region (Schomberg et al., 2006; Reiter et al., 2008). However, cotton residue C/N ratios in our study were likely higher than values we reported because woody stem material was not included in laboratory analyses. Previous research in the southeastern USA has shown that surface-applied cotton residues with a C/N ratio of 39 only mineralized 18 % of N from late December until early May (Lachnicht et al., 2004). In a continuous cotton study in Australia, Rochester et al. (1993) also found that only 1 % of N accumulated by cotton was derived from cotton residues supplied by previous crops and attributed low N recovery to soil N immobilization caused by cotton residue inputs with high C/N ratios. Although cotton was fertilized with 101 kg N ha−1, N availability in former cotton plots at winter wheat

planting was either similar to or lower than the amount available in former fallow plots, indicating there was negligible residual N fertilizer available at winter wheat planting in former cotton plots. Large cotton residue inputs in Jay conceivably led to temporary N immobilization, perhaps explaining cases of lower grain yields, grain N removal, and AE observed at the site. While summer crop had minimal effect on winter wheat performance, this study showed that modest N rates could substantially increase grain yield. The largest percentage increase in grain yield was detected when 34 kg N ha−1 was split-applied. Previous research in the region similarly showed that largest percentage increases in winter wheat grain yields usually occurred at lowest N rates (Frederick and Camberato, 1995). Although winter wheat responded most strongly to the lowest N rate in this study, grain yields obtained at such modest N rates may not be profitable, especially in Citra where optimal N rates (≥ 80 kg N ha-1) resulted in grain yields below 1100 kg ha-1. Nonetheless, observations of grain yield response to such a modest N rate in this study suggests that peanut residues supplied minimal N during winter wheat growth. Applying the model used to describe peanut residue N mineralization (Mulvaney et al., 2017), it was estimated that peanut residues mineralized 15−25 kg N ha−1 during winter wheat growth, which was apparently either insufficient to induce a grain yield response or not mineralized in synchrony with periods of high N demand. These conclusions are supported by earlier research that showed peanut residues were inadequate for meeting optimal N topdressing requirements during peak N demand (Hemwong et al., 2009). Results from this study are aligned with previous research suggesting that peanut N credits to subsequent crops are negligible in the 9

Field Crops Research 249 (2020) 107739

A.D. Jani, et al.

Fig. 5. Winter wheat Grain N removed with harvest in response to fertilization with 0, 34, 67, and 101 kg N ha−1 in former peanut, cotton, and fallow plots. Error bars represent standard errors of the mean. Note: Excessive soil moisture prevented grain harvest in Jay 2016-17.

extended dry period following harvest (Sakonnakhon et al., 2005; Mulvaney et al., 2017). In regions with distinct wet and dry seasons, if N mineralization from peanut residues is delayed due to low soil moisture conditions, then substantial amounts of N would likely be mineralized with the onset of the rainy season and planting of a subsequent crop (Searle et al., 1981; Sakonnakhon et al., 2005; Hemwong et al., 2009). Peanut residues in our study also contained 54–93 kg N ha−1, which is smaller than the range reported (84–146 kg N ha−1) for peanut cultivars in other regions where peanut N credits have been detected (Yano et al., 1994; Hemwong et al., 2009; Sharma and Behera, 2009). Thus, a combination of rainfall patterns and lower peanut residue N content may help explain the lack of detectible peanut credits in the southeastern USA compared to other subtropical and tropical regions. Fig. 6. Agronomic efficiency of winter wheat fertilized with 34, 67, and 101 kg N ha−1 when averaged over summer crop. Within site-year, bars that share the same letter are not significantly different at α = 0.05 according to Tukey’s HSD. Note: Excessive soil moisture prevented grain harvest in Jay 2016-17.

5. Conclusions This study found that peanut did not provide detectible N credits to winter wheat under conservation tillage management in different subtropical growing environments. A large amount of peanut residue N was likely mineralized prior to planting winter wheat and, based on soil inorganic N data, rapidly became unavailable. Additional research is needed to quantify the different biological and environmental pathways by which mineralized N may become unavailable following peanut harvest. A quantitative understanding of different N loss pathways may lead to residue management practices the optimize use of peanut residue N by subsequent crops. While the total amount of N mineralized

southeastern USA. Climatic conditions and possibly peanut cultivar selection may partially explain why peanut N credits have been elusive in the region. Unlike many other peanut-producing regions, there are no distinct wet and dry seasons in the southeastern USA. Considering that N mineralization is largely driven by soil moisture (Agehara and Warncke, 2005; Berg and McClaugherty, 2008; Abera et al., 2012), peanut residues left on the soil surface can potentially mineralize large amounts of N in the southeastern USA relative to regions with an 10

Field Crops Research 249 (2020) 107739

A.D. Jani, et al.

from peanut residues is likely sufficient to induce a grain yield response, the timing and duration at which it is available is likely not in synchrony with winter wheat N demand. Results from this study reveal that peanut N credit recommendations provided by agricultural extension services are not justified and, if followed, will likely result in lower productivity of winter cereals.

N losses and growth of sugarcane. Nutr. Cycl. Agroecosyst. 83, 135–151. Hubbard, R.K., Strickland, T.C., Phatak, S., 2013. Effects of cover crop systems on soil physical properties and carbon/nitrogen relationships in the coastal plain of southeastern USA. Soil Tillage Res. 126, 276–283. Jani, A.D., Mulvaney, M.J., Enloe, H.A., Erickson, J.E., Leon, R.G., Rowland, D.L., Wood, C.W., 2019. Peanut residue distribution gradients and tillage practices determine patterns of nitrogen mineralization. Nutr. Cycl. Agroecosyst. 113, 63–76. Janzen, H., McGinn, S., 1991. Volatile loss of nitrogen during decomposition of legume green manure. Soil Biol. Biochem. 23, 291–297. Jordan, D.L., Barnes, J.S., Corbett, T., Bogle, C.R., Johnson, P.D., Shew, B.B., Koenning, S.R., Ye, W., Brandenburg, R.L., 2008. Crop response to rotation and tillage in peanutbased cropping systems. Agron. J. 100, 1580–1586. Lachnicht, S.L., Hendrix, P.F., Potter, R.L., Coleman, D.C., Crossley Jr, D.A., 2004. Winter decomposition of transgenic cotton residue in conventional-till and no-till systems. Appl. Soil Ecol. 27, 135–142. Large, E.C., 1954. Growth stages in cereals illustration of the Feekes scale. Plant Pathol. 3, 128–129. Larsen, E., Grossman, J., Edgell, J., Hoyt, G., Osmond, D., Hu, S., 2014. Soil biological properties, soil losses and corn yield in long-term organic and conventional farming systems. Soil Tillage Res. 139, 37–45. Larsson, L., Ferm, M., Kasimir-Klemedtsson, A., Klemedtsson, L., 1998. Ammonia and nitrous oxide emissions from grass and alfalfa mulches. Nutr. Cycl. Agroecosyst. 51, 41–46. Maguire, R., Heckendorn, S., 2011. Soil Test Recommendations for Virginia. Virginia Tech, Blacksburg. Meso, B., Balkcom, K.S., Wood, C.W., Adams, J.F., 2007. Nitrogen contribution of peanut residue to cotton in a conservation tillage system. J. Plant Nutr. 30, 1153–1165. Mulvaney, M.J., Wood, C.W., Balkcom, K.S., Shannon, D., Kemble, J.M., 2010. Carbon and nitrogen mineralization and persistence of organic residues under conservation and conventional tillage. Agron. J. 102, 1425–1433. Mulvaney, M.J., Balkcom, K.S., Wood, C.W., Jordan, D., 2017. Peanut residue carbon and nitrogen mineralization under simulated conventional and conservation tillage. Agron. J. 109, 696–705. Noland, R., Lee, D., Buntin, D., Culpepper, S., Harris, G., Martinez, A., Rabinowitz, A.N., 2018. 2017-18 Wheat Production Guide. Univ. of Georgia Coop. Ext., Athens. Overrein, L., Moe, P., 1967. Factors affecting urea hydrolysis and ammonia volatilization in soil. Soil Sci. Soc. Am. J. 31, 57–61. R Development Core Team, 2012. R: A Language and Environment for Statistical Computing. R Foundation for Stat. Comput., Vienna. Reiter, M., Reeves, D., Burmester, C., Torbert, H., 2008. Cotton nitrogen management in a high-residue conservation system: cover crop fertilization. Soil Sci. Soc. Am. J. 72, 1321–1329. Reyes-Cabrera, J., Erickson, J.E., Leon, R.G., Silveira, M.L., Rowland, D.L., Sollenberger, L.E., Morgan, K.T., 2017a. Converting bahiagrass pasture land to elephantgrass bioenergy production enhances biomass yield and water quality. Agric. Ecosyst. Environ. 248, 20–28. Reyes-Cabrera, J., Leon, R.G., Erickson, J.E., Rowland, D.L., Silveira, M.L., Morgan, K.T., 2017b. Differences in biomass and water dynamics between a cotton-peanut rotation and a sweet sorghum bioenergy crop with and without biochar and vinasse as soil amendments. Field Crops Res. 214, 123–130. Rochester, I., Constable, G., MacLeod, D., 1993. Cycling of fertilizer and cotton crop residue nitrogen. Soil Res. 31, 597–609. Sainju, U., Singh, B., Whitehead, W., 2002. Long-term effects of tillage, cover crops, and nitrogen fertilization on organic carbon and nitrogen concentrations in sandy loam soils in Georgia, USA. Soil Tillage Res. 63, 167–179. Sakonnakhon, S.P.N., Toomsan, B., Cadisch, G., Baggs, E., Vityakon, P., Limpinuntana, V., Jogloy, S., Patanothai, A., 2005. Dry season groundnut stover management practices determine nitrogen cycling efficiency and subsequent maize yields. Plant Soil 272, 183–199. Schomberg, H.H., McDaniel, R.G., Mallard, E., Endale, D.M., Fisher, D.S., Cabrera, M.L., 2006. Conservation tillage and cover crop influences on cotton production on a southeastern US coastal plain soil. Agron. J. 98, 1247–1256. Searle, P., Comudom, Y., Shedden, D., Nance, R., 1981. Effect of maize legume intercropping systems and fertilizer nitrogen on crop yielding and residual nitrogen. Field Crops Res. 4, 133–145. Sharma, A., Behera, U., 2009. Recycling of legume residues for nitrogen economy and higher productivity in maize (Zea mays)–wheat (Triticum aestivum) cropping system. Nutr. Cycl. Agroecosyst. 83, 197–210. Sievers, T., Cook, R.L., 2018. Aboveground and root decomposition of cereal rye and hairy vetch cover crops. Soil Sci. Soc. Am. J. 82, 147–155. Sims, G., Ellsworth, T., Mulvaney, R., 1995. Microscale determination of inorganic nitrogen in water and soil extracts. Commun. Soil Sci. Plant Anal. 26, 303–316. Sommer, S.G., Olesen, J.E., Christensen, B.T., 1991. Effects of temperature, wind speed and air humidity on ammonia volatilization from surface applied cattle slurry. J. Agric. Sci. 117, 91–100. Thippayarugs, S., Toomsan, B., Vityakon, P., Limpinuntana, V., Patanothai, A., Cadisch, G., 2008. Interactions in decomposition and N mineralization between tropical legume residue components. Agrofor. Syst. 72, 137–148. Vahdat, E., Nourbakhsh, F., Basiri, M., 2011. Lignin content of range plant residues controls N mineralization in soil. Eur. J. Soil Biol. 47, 243–246. [VDCR] Virginia Department of Conservation and Recreation, 2014. Virginia Nutrient Management Standards and Criteria. Dept. Of Conservation and Recreation. Division of Soil and Water Conservation, Richmond, VA. Weisz, R., 2013. Small Grain Production Guide. North Carolina State Univ., Raleigh. Wright, D., Marois, J., Sprenkel, R., 2011. Production of Ultra Narrow Row Cotton. UF IFAS. Univ. of Florida, Gainesville.

CRediT authorship contribution statement Arun D. Jani: Methodology. Michael J. Mulvaney: Conceptualization, Methodology, Supervision, Writing - review & editing, Validation. John E. Erickson: Methodology, Data curation, Supervision. Ramon G. Leon: Methodology. C. Wesley Wood: Methodology. Diane L. Rowland: Methodology. Heather A. Enloe: Investigation, Supervision, Writing - review & editing. Declaration of Competing Interest The authors declare that there are no conflicts of interest. Acknowledgements This work was supported in part by the Florida Peanut Producers Association, administered through the Florida Department of Agriculture and Consumer Services, and by the USDA National Institute of Food and Agriculture Hatch project FLA-JAY-005475. The authors would particularly like to thank Moo Brown, Porcha Phillips, Jim Boyer, and Greg Kimmons for assistance with this work. Appendix A. Supplementary data Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.fcr.2020.107739. References Abera, G., Wolde-Meskel, E., Bakken, L.R., 2012. Carbon and nitrogen mineralization dynamics in different soils of the tropics amended with legume residues and contrasting soil moisture contents. Biol. Fertil. Soils 48, 51–66. Agehara, S., Warncke, D., 2005. Soil moisture and temperature effects on nitrogen release from organic nitrogen sources. Soil Sci. Soc. Am. J. 69, 1844–1855. Balkcom, K.S., Wood, C.W., Adams, J.F., Wood, B.H., 2004. Composition and decomposition of peanut residues in Georgia. Peanut Sci. 31, 6–11. Balkcom, K.S., Wood, C.W., Adams, J.F., Meso, B., 2007. Suitability of peanut residue as a nitrogen source for a rye cover crop. Sci. Agric. 64, 181–186. Balkcom, K.S., Arriaga, F.J., Balkcom, K.B., Boykin, D.L., 2010. Single-and twin-row peanut production within narrow and wide strip tillage systems. Agron. J. 102, 507–512. Berg, B., McClaugherty, C., 2008. Plant Litter: Decomposition, Humus Formation, Carbon Sequestration, 3rd edn. Springer, Heidelberg. Bundy, L.G., Andraski, T.W., Wolkowski, R.P., 1993. Nitrogen credits in soybean-corn crop sequences on three soils. Agron. J. 85, 1061–1067. Buntin, G.D., Grey, T.L., Harris, G.H., Phillips, D., Prostko, E.P., Raymer, P., Smith, N.B., Sumner, P.E., Woodruff, J., 2007. Canola Production in Georgia. UGA Ext. B. 1331. University of Georgia Cooperative Extension, Athens. Caddel, J., Redfearn, D., Zhang, H., Edwards, J., Deng, S., 2012. Forage Legumes and Nitrogen Production. Oklahoma Cooperative Extension Service No. Oklahoma State University Extension Facts. Cassman, K.G., De Datta, S.K., Amarante, S.T., Liboon, S.P., Samson, M.I., Dizon, M.A., 1996. Long-term comparison of the agronomic efficiency and residual benefits of organic and inorganic nitrogen sources for tropical lowland rice. Exp. Agric. 32, 427–444. Cherr, C., Scholberg, J., McSorley, R., 2006. Green manure as nitrogen source for sweet corn in a warm–temperate environment. Agron. J. 98, 1173–1180. Crozier, C., Hardy, D., Kissel, D., Mitchell, C., Oldham, J., Phillips, S., Sonon, L., 2010. Research-based Soil Testing and Recommendations for Cotton on Coastal Plain Soils. North Carolina State Univ., Raleigh. Ennin, S.A., Clegg, M.D., 2001. Effect of soybean plant populations in a soybean and maize rotation. Agron. J. 93, 396–403. Frederick, J.R., Camberato, J.J., 1995. Water and nitrogen effects on winter wheat in the southeastern Coastal Plain: I. Grain yield and kernel traits. Agron. J. 87, 521–526. Glasener, K., Palm, C., 1995. Ammonia volatilization from tropical legume mulches and green manures on unlimed and limed soils. Plant Soil 177, 33–41. Hemwong, S., Toomsan, B., Cadisch, G., Limpinuntana, V., Vityakon, P., Patanothai, A., 2009. Sugarcane residue management and grain legume crop effects on N dynamics,

11

Field Crops Research 249 (2020) 107739

A.D. Jani, et al.

Yano, K., Daimon, H., Mimoto, H., 1994. Effect of sunn hemp and peanut incorporated as green manures on growth and nitrogen uptake of the succeeding wheat. Jpn. J. Crop Sci. 63, 137–143. Zhao, D., Wright, D.L., Marois, J.J., Mackowiak, C.L., Brennan, M., 2010. Improved growth and nutrient status of an oat cover crop in sod-based versus conventional peanut-cotton rotations. Agron. Sustain. Dev. 30, 497–504.

Wright, D., Tillman, B., Small, I.M., Ferrell, J.A., DuFault, N., 2016a. Management and Cultural Practices for Peanuts. UF IFAS. Univ. of Florida, Gainesville. Wright, D., Blount, A.R., Barnett, R.D., Mackowiak, C.L., Dufault, N., Small, I.M., 2016b. Management Considerations for Wheat Production in Florida. UF IFAS. Univ. of Florida, Gainesville. Wright, D., Marois, J., Rich, J., Rowland, D., Mulvaney, M., 2017. Field Corn Production Guide. UF IFAS. Univ. of Florida, Gainesville.

12