Comparison of conventional, flood irrigated, flat planting with furrow irrigated, raised bed planting for winter wheat in China

Field Crops Research 87 (2004) 35–42

Comparison of conventional, flood irrigated, flat planting with furrow irrigated, raised bed planting for winter wheat in China Wang Fahonga, Wang Xuqinga, Ken Sayreb,* a

Shandong Academy of Agricultural Sciences, Jinan, Shandong 250100, China b CIMMYT Int., Apdo. Postal 6-641, Mexico D.F. 06600 Mexico

Received 2 April 2003; received in revised form 28 August 2003; accepted 2 September 2003

Abstract China is the most populous nation and largest food producer and consumer in the world. In terms of planted area and output, wheat (Triticum aestivum L.) (including both winter and spring habit wheat) is the number one crop in northern China, and currently almost all irrigated wheat is conventionally planted in narrow spaced rows on the flat and is irrigated by flood irrigation within bordered basins. Conventional flat planting for winter wheat has some disadvantages. The use of flood irrigation can result in a low potential irrigation water use efficiency and inefficient use of nitrogen. It can also cause crusting of the soil surface following irrigation and can contribute to the degradation of some soil properties. In addition, it can result in higher levels of crop lodging. A raised bed-planting system with a number of defined rows (usually two to four rows) planted on top of the bed with furrow irrigation was found to overcome these disadvantages. The benefits of the raised bed-planting system with furrow irrigation compared with conventional flat planting with flood irrigation were found as follows: first, there was a savings in some years of as much as 30% of applied irrigation water combined with enhanced water use efficiency by changing from flood to furrow irrigation; second, the crust problem on the soil surface was eliminated and soil physical status was greatly improved; third, nitrogen use efficiency could be improved by 10% or more because of improved nitrogen placement possibilities; fourth, the microclimate within the field was changed due to the orientation of the wheat plants in rows on the beds with the bed-planting system, which reduced crop lodging and decreased the incidence of some wheat diseases. These advantages, interacting together, were found to improve grain quality and increase grain yield by more than 10%. # 2003 Elsevier B.V. All rights reserved. Keywords: Winter wheat; Furrow irrigation; Bed planting; Canopy microclimate; Powdery mildew; Sharp eyespot

1. Introduction In terms of area and output, wheat is the number one crop in northern China. At the same time, winter wheat also has a longer growth period and requires more irrigation compared to other crops, such as maize and *

Corresponding author. Tel.: þ52-55-5804-2004; fax: þ52-55-5804-7558. E-mail address: [email protected] (K. Sayre).

soybean (Yu, 1990). Traditionally, wheat has been conventionally planted on the flat in solid stands and irrigation water management has been by flood irrigation with corresponding low water use efficiency. For example, 1 m3 of water can produce 2.32 kg of grain in Israel, but in China, irrigation water produces <1 kg of grain on the average (Kang and Li, 1997). In addition, flood irrigation with conventional flat planting can cause soil erosion and degradation. Langdale et al. (1979) reported that loss by water erosion of

0378-4290/$ – see front matter # 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.fcr.2003.09.003

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150 mm of topsoil led to 40% annual yield reductions in corn. Buntley and Bell (1976) found yield losses in Tennessee for corn, soybean, wheat, and tall fescue, which were associated with soil erosion, of 42, 50, 28, and 25%, respectively. Flood irrigation with conventional flat planting and excessive nitrogen application can also lead to nitrogen loss and NO3-N pollution of surface and subsurface water (Elmi et al., 2002; Jaynes et al., 2001; Stites and Kraft, 2001). NO3-N levels in excess of 10 mg l1 in groundwater can be associated with health problems and can be encountered in many irrigated areas (Stites and Kraft, 2001). Due to the prevalent intensive cropping systems in China and the trend toward increasing N applications, groundwater NO3-N levels can reach more than 40 mg l1 in some irrigated areas, which can have serious health implications (Li and Lin, 1999). In order to satisfy the tremendous food requirement for China, expansion in area of irrigated farmland and increased use of fertilizers, especially nitrogen fertilizers, is occurring. In Shandong Province, for example, 50 years ago, the area of irrigated wheat was about 250,000 ha, but currently there are over 3,000,000 ha. In accordance with this trend, the amount of irrigation water used has increased from less than 500,000,000 to 8,000,000,000 m3 over the same time period. The amount of nitrogen used has also increased from 6000 t in 1949 to 23,530,000 t at present (Wang et al., 1999; Ren et al., 2001). With both increase in irrigated wheat area and the amount of nitrogen applied, wheat output has increased greatly, but crop lodging and disease are becoming more serious as are other environmental problems. Again taking Shandong Province as an example, powdery mildew disease did not occur on wheat up to 1960, but it has been developing rapidly because of increased irrigation and nitrogen use since 1970. By 1990, the wheat area infected by powdery mildew had increased to about 2,670,000 ha (Yu, 1990). In addition to this problem, the nitrogen use efficiency for wheat is only about 30%, but with proper management it can achieve much higher levels of efficiency (Limon-Ortega et al., 2000; Raun et al., 2002). Since water availability per capita is less than 500 m3 in northern China (Dai and Li, 2000), the increased use of irrigation water and nitrogen application has led to serious environmental problems, including encroachment of seawater combined with

subsiding land surfaces and pollution of groundwater (Xiao et al., 2002). In addition, the total amount of water globally available annually for all purposes is relatively constant, but the high variability, both temporally and spatially, especially in sub-humid, semiarid, and arid regions aggravates patterns of water availability. Water requirements for urban, industrial, environmental, and recreational users increasingly are competing with agriculture for available supplies. The increasing world population, however, requires an ever-increasing supply of food and fiber. To meet this demand, agriculture must produce more with less water, and agriculture must do its share to conserve water so that adequate water will be available for all users. With good management and adoption of appropriate practices, improved agricultural water conservation and subsequent use of that water for greater crop production are possible under both dry land and irrigated condition, thus helping to meet the water needs of all users and providing for food and fiber needs for the increasing global population (Unger and Howell, 1999). Bouaziz and Chekli (1999) reported that proper management could significantly increase the water storage and, consequently, wheat grain yield. Norwood and Dumler (2002) also indicated that use of proper irrigation management could increase water use efficiency and reduce costs. Since China is the most populous nation in the world and also the largest food producer and consumer, there is a clear need to improve both irrigation water use efficiency and nitrogen use efficiency to insure sustainable agricultural development for China. The results below indicate how a bed-planting system using furrow irrigation for wheat can assist in the solution to these issues. Over the past 20 years, farmers in the irrigated production areas in the northwest state of Sonora in Mexico have adopted an innovative system by which wheat is planted in defined rows on top of beds with irrigation supplied in furrows between the beds. Now with more than 95% farmer acceptance of this planting method for wheat as well as all other crops in their cropping systems, dramatic improvements in irrigation water use efficiency have occurred and farmers are taking advantage of the field access provided by this planting method to improve N management (Sayre and Moreno Ramos, 1997; Limon-Ortega et al., 2000). The objective of the research reported

W. Fahong et al. / Field Crops Research 87 (2004) 35–42

here was to compare this bed-planting method using furrow irrigation with the widely used, conventional, flat planting method that uses flood irrigation for winter wheat in Shandong Province in China and to determine its potential utility for the wheat farmers there.

2. Materials and methods The experiment was conducted on the farm at the Shandong Academy of Agricultural Science for four crop cycles (1998–2002). The soil of the plot was light loam. The concentration of organic matter was 1.2%, rapidly available phosphorous was 21 mg kg1, rapidly available potassium was 120 mg kg1, and rapidly available nitrogen was 65 mg kg1. The winter wheat varieties used for experiment, Jimai 19 and Yannong 19, currently are the two most widely planted commercial varieties. These varieties were planted using both flat planting with flood irrigation and bed planting with furrow irrigation. The mount of irrigation water that was applied to each treatment was carefully monitored from the tube well that supplied the irrigation water. Planting date varied from 4 to 10 October and a constant, seedling density of 180 plants m1 was used. One hundred forty kg P ha1 and 36 kg N ha1 were applied as basal fertilizer at planting and 104 kg N ha1 were applied at first node stage. In addition to assess nitrogen use efficiency, a check treatment where no N was applied and a treatment where 207 kg total N ha1 was applied, half at planting as basal with the other half applied at first node stage were included for both varieties and both planting methods. The design of the experiment each year was a randomized complete block with four replications. The width of the bed was 70 cm from furrow bottom to furrow bottom, and three rows of wheat were planted on the top of the beds. The space between each row on the bed was 15 cm. The check treatment for comparison was flat planting (conventional planting), with a row spacing of 22 cm (the most popular practice used by farmers). Planting was carried out with a small planter. The irrigation and fertilization for bed planting was applied in the furrow, and uniformly applied over the surface for flood irrigated, flat planting.

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3. Results and discussion 3.1. The effect of planting and irrigation methods on water use efficiency According to the observations for the four crop cycles, water use efficiency (WUE), based on the amount of grain produced per cubic meter of available water reached 1.96–1.99 kg grain m3 water for bed planting as compared to 1.51–1.67 for flat planting with flood irrigation. Available water used for the WUE determination considered only rainfall and water applied irrigation water. This resulted in a relative increase of 21–32% in WUE, depending on variety, for bed planting with furrow irrigation as compared to conventional planting on the flat with flood irrigation and a corresponding average savings of applied irrigation water of approximately 17% for furrow irrigated, bed planting over the four crop cycles (Table 1). Available water in the soil prior to the initial irrigation at planting and at physiological maturity were measured (data not shown) and were found to be at very similar levels, indicating very little apparent, net contributions by stored, soil water at planting contributing to the estimated WUE values presented in Table 1. 3.2. Planting and irrigation effects on soil porosity and bulk density When compared with the conventional, flat planting system, bed planting decreased the soil surface exposed to flooding by 40%, which eliminated surface soil crusting on the top of the bed where the wheat was planted. In addition, observations showed that soil porosity with bed planting was larger than for flat planting, resulting in lower soil bulk density for bed planting, especially for the 0–10 cm soil profile (Table 2). Over time with additional irrigations, the porosity of the flat planting was reduced and bulk density increased as compared to bed planting (Table 2). 3.3. Nitrogen use efficiency for the different planting systems Post-emerge applied nitrogen fertilizers are normally broadcast on the soil surface with flat planted, flood irrigated wheat but can be band applied into the furrow with bed planting, which can increase the

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Table 1 Comparison of water use efficiency for the different irrigation/planting methods Variety

Planting method

Grain yield (kg ha1)

Rainfall (m3 ha1)

Irrigation water applied (m3 ha1)

Total water available (m3 ha1)

Water use efficiency (kg per m3)

Jimai 19

Bed planting Flat planting

6900 6415

2043 2043

1500 1800

3543 3843

1.96 1.67

Yannong 19

Bed planting Flat planting

7065 5799

2043 2043

1500 1800

3543 3843

1.99 1.51

Mean

–

6544

–

–

–

1.78

LSD (P ¼ 0:05)

–

375

–

–

–

0.29

It is also of interest to note that the total N uptake in the biomass, where no N fertilizer was applied, was consistently and markedly higher for both varieties with bed planting (Table 3).

Table 2 Comparison of bulk density for the different planting methods and two soil depths Date

24 March 1 April 6 May 14 June

Bed planting

Flat planting

0–10 cm

10–20 cm

0–10 cm

10–20 cm

1.11 1.22 1.18 1.20

1.29 1.33 1.31 1.46

1.18 1.38 1.39 1.32

1.35 1.47 1.52 1.50

3.4. Effects of planting method on humidity within the crop canopy The data in Table 4 indicate that the humidity within the crop canopy for bed planting was consistently lower (for both the top of the bed and in the furrow) than the humidity within the crop canopy for flat planting. A reduction in the canopy humidity is conducive to reduce the incidence of some diseases and may enhance better, healthy wheat growth.

nitrogen use efficiency by improved fertilizer N placement. The data in Table 3 indicate that the nitrogen use efficiency (NUE) for bed planting was 23.1% with Jimai 19, and 21.6% with Yannong 19 versus 20.5 and 19.0%. Bed planting increased the nitrogen use efficiency by 12.7 and 13.7% compared with conventional planting even for conditions as encountered here where the inherent available N supplied from the soil in the absence on N fertilizer application ranged from 183 to 202 kg N ha1 in the total biomass (Table 3).

3.5. Effect of planting method on crop lodging and disease incidence Because of the marked changes in plant distribution and orientation that occur with bed planting, major

Table 3 Comparison of nitrogen use efficiency for the different planting methods Variety

Jimai 19

Treatment

Biomass (kg ha1)

N in biomass (%)

Total N in biomass (kg ha1)

Applied N rate (kg ha1)

NUE (%)

NUE increase by bed planting (%) 12.7

Planting method

N use

Bed planting

With N No N With N No N

16438 14851 15156 12283

1.52 1.36 1.44 1.43

250 202 218 176

207 0 207 0

23.1 – 20.5 –

With N No N With N No N

16750 15039 15621 13132

1.56 1.44 1.42 1.39

261 217 222 183

207 0 207 0

21.6 – 19.0 –

Flat planting Yannong 19 Bed planting Flat planting

13.7

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Table 4 Canopy humidity (%) at different dates for the different planting methods Variety

Planting method

Position of measurement

23 April

2 May

9 May

16 May

23 May

Jimai 19

Bed planting

Bed-top Furrow Average Average

65 59 62 71

71 62 67 79

76 65 71 84

79 73 76 85

84 73 79 93

67 62 65 72

72 65 69 77

87 67 77 84

88 78 83 86

83 74 79 88

3

4

4

3

3

Flat planting Yannong 19

Bed planting

Flat planting

Bed-top Furrow Average Average

LSD (P ¼ 0:05)

–

–

modifications in the canopy microclimate can take place as was seen above for canopy humidity. These canopy microclimate modifications may lead to changes in stem characteristics associated with crop lodging and may result in reductions in incidence of some prevalent diseases. Table 5 indicates that bed planting reduced plant height by 4–7.5 cm, with the length of the basal first and second nodes being shortened by 1.7–4.4 cm. The incidence of sharp eye spot disease caused by Pseudocercosporella herpotrichoides was decreased by 75.5 and 96.5% and powdery mildew caused by Erysiphe graminis was decreased by 60.7 and 59.6% by bed planting for Jimai 19 and Yannong 19, respectively, when compared with flat planting. The level of lodging just before harvest was 70% for Yannong 19 and 10% for Jimai 19 with flat planting condition versus 5 and 0%, respectively, with bed planting (Table 5).

3.6. Differential flag leaf chlorophyll levels and trends from the two different planting methods The content of chlorophyll is a very important indicator of photosynthetic potential. Table 6 shows that the chlorophyll levels, as measured by the SPAD meter, were consistently higher for bed planting as compared to flat planting at all stages of wheat development and growth, but especially during the later stages of the grain-fill period. The higher flag leaf chlorophyll levels for bed planting is likely associated with the more efficient N uptake efficiency as indicated in Table 4 above and may be associated with better photosynthetic leaf function, especially as seen in Table 6 during late grain filling which may lead to a longer ‘‘stay-green’’ period, longer grain-fill interval and corresponding higher grain yield.

Table 5 Effect of the different planting methods on plant height, first and second internode length (Len.) and dry matter weight (cm1), sharp eye spot and powdery mildew incidence and crop lodging Variety

Planting method

Plant height (cm)

First internode

Second internode

Len. (cm)

Dry weight (mg cm1)

Len. (cm)

Dry matter (mg cm1)

Sharp eye spot (%)

Powdery mildew (%)

Lodging (%)

Jimai 19

Bed planting Flat planting

73.0 77.0

2.8 3.6

17.8 16.1

4.2 5.3

21.4 19.7

7.9 32.6

7.7 19.6

0 10

Yannong 19

Bed planting Flat planting

76.0 83.5

4.7 5.1

17.3 12.9

7.7 8.7

18.6 15.2

1.8 51.2

9.2 22.8

5 70

LSD (P ¼ 0:05)

–

3.8

0.3

1.0

0.7

1.0

11.7

4.6

3

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Table 6 Comparison of the chlorophyll content (SPAD units) in the flag leaf for the different planting systems from flag leaf emergence until physiological maturity

Table 8 Comparison of the grain-filling rate (g per 1000 grains per day) at different times during the grain-fill period for the different planting methods

Date

Bed planting

Flat planting

Date

Bed planting

Flat planting

26 April 4 May 10 May 17 May 24 May 26 May 28 May

52.9 55.9 54.4 54.5 38.0 24.3 9.9

49.7 52.5 52.8 52.7 37.4 11.1 8.4

11 18 25 31

1.27 2.66 1.34 0.10

1.06 2.21 0.86 0

May May May May

canopy top and ground level were not determined, they still provide another avenue to assess differences in input use related to the different planting and associated irrigation systems.

3.7. Effects of planting method on solar radiation use efficiency

3.8. Effects of planting method on grain fill, grain yields and grain quality

The dry biomass yields for the 2000/2001 crop cycle for Jimai 19 and Yannong 19 were 15,570 and 16,134 kg ha1, respectively, under the bed-planting system, which resulted in a total, incident solar radiation conversion efficiency of 0.910 and 0.943 for total biomass production, respectively. Dry biomass yields for the same two varieties were 14,109 and 14,550 kg ha1, respectively, under the flat planting system, providing a total, incident solar radiation conversion efficiency of 0.825 and 0.851, respectively. Compared with the flat planting, the total, incident solar conversion efficiency for biomass was increased by 10.3–10.8% under the bed-planting condition, while for grain yield the bed-planting advantage ranged from 10.0 to 13.8% (Table 7). Although this estimate of solar radiation use simply based on total incident solar radiation is very approximate since actual intercepted solar radiation values between

Results presented in Tables 8 and 9 indicate that the rate of grain filling for bed planting was much higher during different stages of the grain-fill period than for the flat planting. In addition to this, bed planting also appreciably prolonged the grain-fill period. Since bed planting reduced plant height and led to decreased humidity within the canopy, this appears to have resulted in corresponding decreases in the crop lodging and reductions in disease incidences. Grain yields for the two varieties were increased by 10.0– 13.4% by bed planting as compared with flat planting. Some yield components were also affected—grains per spike increased 8.3–12.15% and grain weight increased 7.5–7.3% but there was no effect of planting method on spikes per square meter and harvest index.

Table 7 Comparison of the total, incident solar radiation conversion efficiency for biomass and grain yields for the different varieties and planting methods for only the 2000/2001 crop cycle (total, incident solar radiation measured above the crop canopy was 3,043,152 MJ ha1, non-grain dry matter was assumed to contain 14.6 MJ ha1 and dry grain was assumed to contain 17.8 MJ ha1) Variety

Planting method

Biomass yield (kg ha1)

Grain yield (kg ha1)

Energy in grain (MJ ha1)

Energy in biomass (MJ ha1)

Radiation conversion efficiency in grain (%)

Radiation conversion efficiency in biomass (%)

Jimai 19

Bed planting Flat planting

15570 14109

6195 5629

110209 100149

276990 250999

0.362 0.329

0.910 0.825

Yannong 19

Bed planting Flat planting

16134 14550

6765 5965

120349 106126

287023 258844

0.395 0.349

0.943 0.851

LSD (P ¼ 0:05)

–

987

404

8788

19876

0.014

0.054

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Table 9 Effect of planting methods on grain yield and yield components of wheat Variety

Planting method

Spikes (m2)

Grains per spike

Grain weight (g)

Grain yield (kg ha1)

Yield increase by bed planting (%)

Harvest index

Jimai 19

Bed planting Flat planting

453 448

43.1 39.8

38.7 36.0

6195 5629

10.0 –

0.40 0.40

Yannong 19

Bed planting Flat planting

633 616

36.1 32.2

36.6 34.1

6765 5965

13.4 –

0.42 0.41

LSD (P ¼ 0:05)

–

28

2.0

1.8

312

–

0.15

Bed planting improved the conditions for wheat growth and development, which also enhanced the grain quality. Grain test weight was 78.3 kg hl1 for Jimai 19 and 74.7 kg hl1 for Yannong 19 under the bed-planting system but was reduced to 76.8 and 72.1 kg hl1, respectively, with flat planting. For bed planting, the protein content of Jimai 19 was 13.5% and it was 13.2% for Yannong 19, but for flat planting, the protein contents were 13.4 and 12.8%, respectively. Bed planting resulted in both increases in yield as well as grain protein content, which is rarely observed for wheat production situations.

N use by bed-planting system directly affected the higher bed planted, grain yields by extension of the grain-fill period by providing conditions for a longer, ‘‘stay-green’’ leaf period. Fourth, the bed-planting system decreased the humidity in the crop canopy, which is helpful to reduce disease incidences as well as crop lodging. The results of this research confirm that bed planting is fully suitable for irrigated winter wheat production in Shandong, and offers a sound opportunity for sustainable farming.

References 4. Conclusions The research that has been conducted for four crop cycles based on an irrigated winter wheat production system in Shandong, China has indicated that there are many advantages with the bed planted, furrow irrigated system: first, changing from flat planting with flood irrigation to raised bed planting with furrow irrigation improved water use efficiency by 21–30% combined with an approximate 17% savings in applied irrigation water. This has tremendous implications in the drastically irrigation water-challenged Yellow River basin. Second, bed planting also appeared to enhance some soil physical properties, thereby providing a better condition for wheat establishment, growth and development. Third, bed planting makes it possible to apply post-emerge nitrogen by band incorporation in the furrow before irrigation as opposed to broadcast, surface application, which improved nitrogen use efficiency by 10–15% even for soil conditions with high N supplying capacity. Use of this technology under more N limited soil conditions should further enhance N use efficiency. It was also apparent that the improved

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