- Email: [email protected]
The effect of seeding and tillage methods on productivity of rice–wheat cropping system
Soil & Tillage Research 61 (2001) 125–131
The effect of seeding and tillage methods on productivity of rice–wheat cropping system Surendra Singh, S.N. Sharma, Rajendra Prasad* Division of Agronomy, Indian Agricultural Research Institute, New Delhi 110 012, India Received 9 May 2000; received in revised form 31 August 2000; accepted 8 November 2000
Abstract Many farmers in southeast Asia are growing rice on unpuddled soil. This practice does not permit breaking of the deadlock of increase in productivity in spite of using high yielding varieties and practising all known scientific technologies. Furthermore, farmers do dry seeding which leads to heavy infestation of weeds and reduces response to other inputs. Similarly, in rice–wheat belt due to short turn around time farmers resort to broadcast sowing of wheat after rice and no data on benefits or otherwise of tillage are available. A field study was therefore conducted for 3 years (1993–1994 to 1995–1996) at the Indian Agricultural Research Institute, New Delhi to study the effect of tillage and seeding methods in rice–wheat cropping system. Treatments included four combinations of two puddling treatments (puddling and no puddling) and two methods of rice seeding (direct seeding and transplanting) in rice and two tillage treatments (zero and conventional tillage) in wheat. Results indicated that puddling increased grain yield of rice by 0.7–1 t ha1 and of succeeding wheat by 0.2–0.4 t ha1, straw yield of rice by 0.8–1.7 t ha1 and of succeeding wheat by 0.1–1.0 t ha1. Puddling reduced water requirement of rice by 75 mm ha and increased net return of rice–wheat system by US $175 ha1. Transplanted rice gave significantly higher grain and straw yields and net returns than direct seeded rice both on puddled and unpuddled seedbed. Conventional tillage in wheat also increased productivity of rice–wheat cropping system significantly over zero tillage after both puddled and non-puddled rice. Our results thus show that rice should be grown on puddled soil and wheat after rice should be sown after conventional tillage. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Puddling; Transplanting; Direct seeding; Productivity; Water requirement; Economics
1. Introduction In most lowland regions of Asian countries rice is grown as a transplanted crop in contrast to the direct seeding in USA, Australia and parts of Europe. Transplanting requires a soft seedbed and therefore wetland tillage or puddling is done. Bodman and Rubin (1948) defined puddling as the mechanical reduction in *
Corresponding author. Tel.: þ91-011-5814538; fax: þ91-011-5742283. E-mail address: [email protected] (R. Prasad).
apparent specific volume of soil. They also introduced the puddlability, a factor influenced by the soil moisture and energy status of the solid phase. Puddling has a number of advantages, which include weed control, care of transplanting, and reduction in percolation loss of water and nutrients. However, it is a capital and energy intensive process and requires a large volume of water (Sharma and De Datta, 1986). In the rice–wheat cropping system belt covering about 12 million ha in north-eastern India (Kumar et al., 1998), rice is a non-traditional crop and its cultivation began in 1970s with the introduction of
0167-1987/01/$ – see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 - 1 9 8 7 ( 0 0 ) 0 0 1 8 8 - 4
126
S. Singh et al. / Soil & Tillage Research 61 (2001) 125–131
high yielding dwarf wheats from CIMMYT, Mexico that required lower temperatures for germination. As a result, wheat sowings had to be shifted from midOctober to mid-November, providing one extra month to the preceding rainy season crop. Since high yielding rice varieties introduced from IRRI in the Philippines were already available, rice cultivation began in northwestern India and the rice (July–November)–wheat (November–April) two crops a year cropping system yielding 7–12 t ha1 set in. Today this cropping system is the backbone of India’s food security. Farmers in this non-traditional rice belt were not familiar with starting rice in a nursery, puddling and transplanting. Starting rice in nurseries and transplanting were well accepted due to the lesser seed requirement; 25– 30 kg ha1 as compared with 75–100 kg ha1 needed for direct seeding. However, due to the large water requirement and high energy input many farmers do not practice puddling and rice seedlings are transplanted in fields that receive one dry cultivation followed by flooding. Comparative data for direct seeding and puddled transplanted rice are not available. The tillage problem in the rice–wheat cropping system does not end with rice. As soon as rice is harvested in the first or second week of November, wheat has to be seeded as soon as possible; the optimum for wheat seeding is mid-November. However, wheat seeding generally is delayed due to moist field conditions, which makes cultivation impossible. Many farmers therefore broadcast wheat in moist fields left after rice harvest. This also permits them to take advantage of residual moisture in rice fields and permits timely sowing of wheat. Traditional cultivation of land and sowing wheat generally delays wheat sowings to late November or early December resulting in reduced yield. However, yields are also low in direct seeded wheat due to serious weed problem; very few farmers use herbicides because they are fairly expensive. The present study was therefore conducted to compare: (1) puddling vs. no puddling; (2) direct seeding vs. transplanting of rice; (3) tillage vs. no tillage in wheat.
2. Materials and methods A field experiment was conducted for 3 years (1993–1994 to 1995–1996) at the experimental farm
of the Indian Agricultural Research Institute, New Delhi, on a sandy clay loam Fluvent. The soil of the experimental field had a pH of 7.9, organic C at 0.55%, 0.5 M NaHCO3 extractable P at 30 kg ha1 and 1 N ammonium acetate extractable K at 320 kg ha1 as determined by procedures described by Prasad (1998). During the rice season the experiment was laid out in a factorial randomized block design with the four combinations of puddling or no puddling and direct seeding or transplanting of rice. There were three replications and the plot size for rice was 20:0 10:0 m2 . During the succeeding wheat season each rice plot was divided into two sub-plots and wheat was broadcast with no tillage or drilled after tillage. In plots where puddling was not done, the soil was cultivated while it was dry. The plots were then filled with water and sprouted rice seeds were broadcast or rice seedlings were transplanted. Puddling was done by flooding the plots and rotovating followed by levelling. This operation was repeated three times. Transplanting or sprouted rice seed sowing was then done. The rice variety was Pusa 834 and three 25-dayold seedlings were transplanted at 20 cm inter-row and 10 cm intra-row spacing or 75 kg ha1 seed was broadcast. Plots for direct seeding of rice were prepared and sowing was done at the same time when nursery sowing was done, i.e. about a month in advance of date of transplanting. Direct seeding was thus done in the first week of June while transplanting was done in the first week of July. The water regime in all plots was maintained between saturation and flooding up to 5 cm standing water. The water applied in different treatments was measured with Parshall flume fixed at the start of the main channel of plots. Rice was harvested in the last week of October. Tillage for wheat involved two discings and levellings as soon as the field came to cultivation after rice harvest. Wheat was drilled with a seed drill in no-till or tilled plots the same day to avoid differences in yield due to date of sowing. Wheat variety used was HD 2329. Wheat was sown in the third week of November and harvested in the second week of April, the following year. Rice received 100 kg N as urea, 40 kg P2O5 as ordinary superphosphate, 40 kg K2O as muriate of potash and 25 kg zinc sulphate per hectare. Nitrogen was applied in two doses; half at sowing/transplanting and the other half at panicle initiation. Wheat received
S. Singh et al. / Soil & Tillage Research 61 (2001) 125–131
127
Table 1 Total monthly rainfall at New Delhi
100 kg N as urea, 40 kg P2O5 as ordinary superphospahte and 40 kg K2O as muriate of potash per hectare. Nitrogen was applied in two doses, half at sowing and the other half at first irrigation (25 days after sowing). Wheat received 3–5 irrigations.
Month
3. Results and discussion 3.1. Grain yield Although the crops were raised under irrigation natural rainfall still controls crop yields. In 1993– 1994 and 1994–1995 July rainfall was very good and it encouraged rapid vegetative growth, which finally showed up in grain yield (Table 1). In 1995–1996 July rainfall was much below the normal and rice crop, in general, was adversely affected. Furthermore, heavy rainfall in September, when the rice crop was at flowering stage adversely affected the crops. This explains why rice grain yield was the lowest in 1995– 1996. Wheat yield in 1994–1995 and 1995–1996 was also adversely affected by relatively more rain than in 1993–1994 in January, when the reproductive phase begins in the crop. Puddling significantly increased grain yield of rice as well as of the succeeding wheat crop (Table 2); the increase ranged from 0.7 to 1 t ha1 in rice and from 0.2 to 0.4 t ha1 in wheat. Thus total gain by puddling ranged from 0.9 to 1.4 t ha1 in rice–wheat cropping system. In an experiment at the International Rice
Total monthly rainfall (mm) 1993–1994
1994–1995
1995–1996
July August September October November December January February March April
305.0 160.8 227.0 0.0 0.0 0.0 10.4 9.2 8.8 4.0
450.6 171.1 3.4 0.0 0.0 0.0 66.6 22.0 20.6 0.0
70.6 432.2 184.4 0.0 0.0 1.8 80.4 10.2 5.4 0.0
Total
725.2
734.3
785.0
Research Institute, Philippines also irrigated rice yielded 7.9 t ha1 in a puddled soil but yielded only 3.6 t ha1 in a non-puddled soil (De Datta et al., 1973). The increase in productivity of rice–wheat cropping system by puddling may be due to better control of weeds (De Datta and Barker, 1978), maintenance of suitable water regime (Singh et al., 1995) and creation of anaerobic soil conditions (Ponnamperuma, 1972). Although a weed count was not made in the present study, there were lesser weeds in puddled plots than in unpuddled plots. Reddy and Hukkeri (1980a) also observed that increase in rice yield due to puddling was largely due to lesser weed growth due to puddling.
Table 2 Effect of puddling and method of seeding of rice on grain yield (t ha1) of rice and succeeding wheat Treatment
1993–1994
1994–1995
1995–1996
Rice
Wheat
Total
Rice
Wheat
Total
Rice
Wheat
Total
No puddling Direct seeding Transplanting
3.2 3.4
3.9 4.4
7.1 7.8
3.2 4.1
3.1 3.0
6.3 7.1
2.7 3.4
3.0 3.2
5.7 6.6
Mean
3.3
4.1
7.4
3.6
3.0
6.6
3.0
3.1
6.1
Puddling Direct seeding Transplanting
3.8 4.2
4.4 4.6
8.2 8.8
4.4 4.8
3.3 3.3
7.7 8.1
3.1 4.4
3.5 3.2
6.6 7.6
Mean
4.0
4.5
8.5
4.6
3.3
7.9
3.7
3.3
7.0
LSD ðP ¼ 0:05Þ for puddling LSD ðP ¼ 0:05Þ for puddling seeding
0.57 0.80
0.11 0.15
– –
0.88 1.25
0.29 0.42
– –
0.17 0.24
0.54 NS
– –
128
S. Singh et al. / Soil & Tillage Research 61 (2001) 125–131
3.2. Straw yield Puddling increased straw yield of rice (0.7– 1.7 t ha1) and of succeeding wheat (0.1–0.5 t ha1) significantly (Table 4). Thus total gain in straw yield by puddling in rice–wheat system ranged from 1.2 to 1.8 t ha1. Transplanting rice resulted in significantly more straw than direct seeded rice (Fig. 2). Like grain, the highest straw yield of rice and wheat was obtained when rice was transplanted on puddled soil and the lowest when rice was seeded directly on unpuddled soil. Transplanting of rice increased total straw yield of rice–wheat cropping system over direct seeded rice by 1.2–1.9 t ha1 on unpuddled soil and by 1.5– 2.3 t ha1 on puddled soil. Similarly puddling increased total straw yield of rice–wheat system over no puddling by 1.2–1.4 t ha1 when rice was transplanted and by 1.1–2.6 t ha1 when rice was direct seeded. Tillage for wheat increased straw yield over zero tillage in 2 out of 3 years; the increase ranged from 0.2 to 0.5 t ha1 (Table 3).
Fig. 1. Effect of method of seeding of rice on the grain yield (t ha1) of rice–wheat cropping system.
3.3. Water management
Method of rice seeding also significantly influenced grain yield of rice (Fig. 1). Transplanted rice yielded 0.2–1.3 t ha1 more grain than direct seeded rice. The highest grain yield for the rice–wheat cropping system was obtained when rice was transplanted on puddled soil; 0.4–1.0 t ha1 more than for direct seeded puddled rice, 1 t ha1 more than for transplanted unpuddled rice and 1.7–1.9 t ha1 more than for direct seeded unpuddled rice. Tillage also increased grain yield of wheat over that obtained with zero tillage by 0.4 t ha1 in the first year and 0.5 t ha1 in the second year. However, in the third year the effects of tillage on grain yield of wheat were not significant (Table 3).
Data on water requirement and water use efficiency (WUE) are given in Table 5. Puddling curtailed water requirement of rice by 75 mm ha mainly because of less percolation losses in puddled plots than in unpuddled plots. This resulted in higher WUE (2.8 kg grain mm ha1 water) with puddling as compared to without puddling (2.2 kg grain mm ha1 water). Method of rice seeding had no significant effect on water requirement of rice; however, transplanted rice required more water than direct seeded rice on unpuddled soil, whereas on puddled soil it was vice versa. It was due to the fact that rice was direct
Table 3 Effect of tillage in wheat on grain and straw yield (t ha1) Treatment
1993–1994
1994–1995
1995–1996
Grain
Straw
Total
Grain
Straw
Total
Grain
Straw
Total
Zero tillage Conventional tillage
4.2 4.6
6.3 6.8
10.5 11.4
3.6 4.1
4.3 4.6
7.9 8.7
3.2 3.3
4.8 5.0
8.0 8.3
LSD ðP ¼ 0:05Þ
0.17
0.25
–
0.09
0.17
–
NS
NS
–
S. Singh et al. / Soil & Tillage Research 61 (2001) 125–131
129
Table 4 Effect of puddling and method of seeding of rice on straw yield (t ha1) of rice and succeeding wheat Treatment
1993–1994
1994–1995
1995–1996
Rice
Wheat
Total
Rice
Wheat
Total
Rice
Wheat
Total
No puddling Direct seeding Transplanting
5.9 7.0
5.7 6.5
11.6 13.5
6.0 8.0
4.0 4.6
10.0 12.6
5.5 6.1
4.6 5.1
10.1 11.2
Mean
6.4
6.3
12.7
7.0
4.3
11.3
5.8
4.8
10.6
Puddling Direct seeding Transplanting
6.3 7.9
6.7 7.0
13.0 14.9
7.7 8.8
4.5 4.9
12.2 13.7
6.5 8.6
5.0 4.8
11.5 13.4
Mean
7.1
6.8
13.9
8.2
4.7
12.9
7.5
4.9
12.4
LSD ðP ¼ 0:05Þ for puddling LSD ðP ¼ 0:05Þ for puddling seeding
0.98 1.38
0.30 0.42
– –
1.34 1.99
0.24 0.34
– –
0.31 0.44
NS NS
– –
seeded on dry and unpuddled soil and required only 2–3 irrigations during seedling stage (30 days), whereas when rice was direct seeded on puddled soil it required irrigations on alternate days even during seedling stage. This could be mainly because when rice was direct seeded in unpuddled soils its roots went deeper in soil as in upland rice and could obtain water
from lower soil layers. On the other hand, root system in direct seeded puddled soil remained restricted to the surface layer only and thus could not obtain water from lower soil layers and called for frequent irrigation. However, WUE was always higher in transplanted rice than direct seeded rice mainly because of higher grain yield in the former than in the latter (Table 2). Our results are in conformity with those of De Datta et al. (1973) who reported that crop in puddled soil produced 9.0 kg grain mm ha1 water, while the crop on non-puddled soil produced only 8.3 kg grain mm ha1 water. Reddy and Hukkeri (1980b) also reported higher efficiency of irrigation water due to puddling. 3.4. Economics
Fig. 2. Effect of method of seeding of rice on the straw yield (t ha1) of rice–wheat cropping system.
Puddling increased gross income over no puddling by US $108 ha1 in rice and US $39 ha1 in wheat and reduced cost of rice cultivation by US $27 ha1 (Table 6). The growing of rice without puddling resulted in a net loss of US $29 ha1, whereas growing a rice crop on puddled soil gave a net return of US $106 ha1. Since the cost of cultivation of wheat was the same (US $290 ha1) after puddled and unpuddled rice, wheat after puddled rice gave US $39 ha1 more net return than wheat after unpuddled rice. Thus puddling increased net return of rice–wheat system by US $174 ha1. Transplanting of rice also increased gross return of both rice and succeeding wheat as compared to direct
130
S. Singh et al. / Soil & Tillage Research 61 (2001) 125–131
Table 5 Effect of puddling and method of seeding of rice on irrigation water requirement (IWR) and water use efficiency (WUE) of rice–wheat cropping system (mean over 3 years) Treatment
Rice
Wheat
Total
IWR (mm ha)
WUE (kg grain mm ha1 water)
IWR (mm ha)
WUE (kg grain mm ha1 water)
IWR (mm ha)
WUE (kg grain mm ha1 water)
No puddling Direct seeding Transplanting
1500 1575
2.0 2.2
400 400
8.2 8.7
1900 1975
3.3 3.6
Mean
1537
3.1
400
8.4
1937
3.4
Puddling Direct seeding Transplanting
1475 1450
2.6 3.1
400 400
9.2 9.2
1875 1850
4.0 4.4
Mean
1462
2.8
400
9.2
1862
4.2
Table 6 Effect of puddling and method of seeding of rice on economic return (US $ ha1) of rice–wheat cropping system (mean over 3 years of study)a Treatment
Rice
Wheat
Gross income
Cost of cultivation
No puddling Direct seeding Transplanting
428 514
516 485
Mean
471
Puddling Direct seeding Transplanting Mean
Net income
Total
Gross income
Cost of cultivation
Net income
Gross income
Cost of cultivation
Net cultivation
88 29
577 620
290 290
287 330
1005 1134
806 775
199 359
500
29
598
290
308
1069
790
279
528 631
471 476
57 155
647 647
290 290
357 357
1175 1278
761 766
414 512
579
473
106
647
290
357
1226
763
463
a Gross income was calculated on the basis of Government of India procurement price: rice grain @ US $117.5 t1, wheat grain @ US $137.5 t1 and prevailing price of straw @ US $1.25 t1 and wheat straw @ US $2.50 t1. Cost of cultivation was calculated on the basis of prevailing prices of different inputs.
seeding. The cost of cultivation of transplanted rice was less than direct seeded rice on unpuddled soil and more on puddled soil. This difference was due to heavy weed infestation in unpuddled direct seeded rice as compared to unpuddled transplanted rice. Puddling reduced weed population in rice and hence transplanting on puddled soil involved no extra cost of weed control. The net return from rice–wheat cropping system was the highest when rice was transplanted on puddled soil and the lowest when rice was directly seeded on unpuddled soil. Transplanting of rice increased net return of rice–wheat system by US $100 ha1 with puddling and by US $152 ha1 with-
out puddling. Similarly, puddling increased net return of rice–wheat cropping system by US $200 ha1 when rice was direct seeded and US $148 ha1 when rice was transplanted.
4. Conclusions Our results show that rice yields are the highest when it is transplanted on puddled land. Even if rice is seeded directly it should be seeded on puddled land. Again for high yields wheat after rice should be sown after conventional tillage.
S. Singh et al. / Soil & Tillage Research 61 (2001) 125–131
References Bodman, G.B., Rubin, J., 1948. Soil puddling. Soil Sci. Soc. Am. Proc. 13, 27–36. De Datta, S.K., Barker, B., 1978. Land preparation for rice soil. In: Soil and Rice. International Rice Research Institute, Los Banos, Philippines, pp. 623–648. De Datta, S.K., Krupp, H.K., Alvarez, E.I., Modgal, S.C., 1973. Water management practices in flooded tropical rice. In: Water Management in Philippines Irrigation Systems: Research and Operations. International Rice Research Institute, Los Banos, Philippines, pp. 1–18. Kumar, P., Josh, P.K., Johansen, C., Asokan, M., 1998. Suitability of rice–wheat based cropping system. In: India — Socioeconomic and Policy Issues. Economic and Political Weekly 33, September 26, pp. 152–158.
131
Ponnamperuma, F.N., 1972. The chemistry of submerged soils. Adv. Agron. 29, 29–96. Prasad, R., 1998. A Practical Manual for Soil Fertility. Division of Agronomy, Indian Agricultural Research Institute, New Delhi. Reddy, S.R., Hukkeri, S.B., 1980a. Increasing effectiveness of fertilizers through weed control in direct seeded irrigated rice. Fert. News 25, 30–33. Reddy, S.R., Hukkeri, S.B., 1980b. Effect of tillage practices on irrigation requirement, weed control and yield of lowland rice. Soil Till. Res. 3, 147–158. Sharma, P.K., De Datta, S.K., 1986. Physical properties and processes of puddled rice soils. Adv. Soil Sci. 5, 139–178. Singh, R., Gajri, P.R., Gill, K.S., Khera, R., 1995. Puddling intensity and nitrogen use efficiency of rice (Oryza sativa) on a sandy loam soil of Punjab. Indian J. Agric. Sci. 65, 749–751.
The effect of seeding and tillage methods on productivity of rice–wheat cropping system Surendra Singh, S.N. Sharma, Rajendra Prasad* Division of Agronomy, Indian Agricultural Research Institute, New Delhi 110 012, India Received 9 May 2000; received in revised form 31 August 2000; accepted 8 November 2000
Abstract Many farmers in southeast Asia are growing rice on unpuddled soil. This practice does not permit breaking of the deadlock of increase in productivity in spite of using high yielding varieties and practising all known scientific technologies. Furthermore, farmers do dry seeding which leads to heavy infestation of weeds and reduces response to other inputs. Similarly, in rice–wheat belt due to short turn around time farmers resort to broadcast sowing of wheat after rice and no data on benefits or otherwise of tillage are available. A field study was therefore conducted for 3 years (1993–1994 to 1995–1996) at the Indian Agricultural Research Institute, New Delhi to study the effect of tillage and seeding methods in rice–wheat cropping system. Treatments included four combinations of two puddling treatments (puddling and no puddling) and two methods of rice seeding (direct seeding and transplanting) in rice and two tillage treatments (zero and conventional tillage) in wheat. Results indicated that puddling increased grain yield of rice by 0.7–1 t ha1 and of succeeding wheat by 0.2–0.4 t ha1, straw yield of rice by 0.8–1.7 t ha1 and of succeeding wheat by 0.1–1.0 t ha1. Puddling reduced water requirement of rice by 75 mm ha and increased net return of rice–wheat system by US $175 ha1. Transplanted rice gave significantly higher grain and straw yields and net returns than direct seeded rice both on puddled and unpuddled seedbed. Conventional tillage in wheat also increased productivity of rice–wheat cropping system significantly over zero tillage after both puddled and non-puddled rice. Our results thus show that rice should be grown on puddled soil and wheat after rice should be sown after conventional tillage. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Puddling; Transplanting; Direct seeding; Productivity; Water requirement; Economics
1. Introduction In most lowland regions of Asian countries rice is grown as a transplanted crop in contrast to the direct seeding in USA, Australia and parts of Europe. Transplanting requires a soft seedbed and therefore wetland tillage or puddling is done. Bodman and Rubin (1948) defined puddling as the mechanical reduction in *
Corresponding author. Tel.: þ91-011-5814538; fax: þ91-011-5742283. E-mail address: [email protected] (R. Prasad).
apparent specific volume of soil. They also introduced the puddlability, a factor influenced by the soil moisture and energy status of the solid phase. Puddling has a number of advantages, which include weed control, care of transplanting, and reduction in percolation loss of water and nutrients. However, it is a capital and energy intensive process and requires a large volume of water (Sharma and De Datta, 1986). In the rice–wheat cropping system belt covering about 12 million ha in north-eastern India (Kumar et al., 1998), rice is a non-traditional crop and its cultivation began in 1970s with the introduction of
0167-1987/01/$ – see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 - 1 9 8 7 ( 0 0 ) 0 0 1 8 8 - 4
126
S. Singh et al. / Soil & Tillage Research 61 (2001) 125–131
high yielding dwarf wheats from CIMMYT, Mexico that required lower temperatures for germination. As a result, wheat sowings had to be shifted from midOctober to mid-November, providing one extra month to the preceding rainy season crop. Since high yielding rice varieties introduced from IRRI in the Philippines were already available, rice cultivation began in northwestern India and the rice (July–November)–wheat (November–April) two crops a year cropping system yielding 7–12 t ha1 set in. Today this cropping system is the backbone of India’s food security. Farmers in this non-traditional rice belt were not familiar with starting rice in a nursery, puddling and transplanting. Starting rice in nurseries and transplanting were well accepted due to the lesser seed requirement; 25– 30 kg ha1 as compared with 75–100 kg ha1 needed for direct seeding. However, due to the large water requirement and high energy input many farmers do not practice puddling and rice seedlings are transplanted in fields that receive one dry cultivation followed by flooding. Comparative data for direct seeding and puddled transplanted rice are not available. The tillage problem in the rice–wheat cropping system does not end with rice. As soon as rice is harvested in the first or second week of November, wheat has to be seeded as soon as possible; the optimum for wheat seeding is mid-November. However, wheat seeding generally is delayed due to moist field conditions, which makes cultivation impossible. Many farmers therefore broadcast wheat in moist fields left after rice harvest. This also permits them to take advantage of residual moisture in rice fields and permits timely sowing of wheat. Traditional cultivation of land and sowing wheat generally delays wheat sowings to late November or early December resulting in reduced yield. However, yields are also low in direct seeded wheat due to serious weed problem; very few farmers use herbicides because they are fairly expensive. The present study was therefore conducted to compare: (1) puddling vs. no puddling; (2) direct seeding vs. transplanting of rice; (3) tillage vs. no tillage in wheat.
2. Materials and methods A field experiment was conducted for 3 years (1993–1994 to 1995–1996) at the experimental farm
of the Indian Agricultural Research Institute, New Delhi, on a sandy clay loam Fluvent. The soil of the experimental field had a pH of 7.9, organic C at 0.55%, 0.5 M NaHCO3 extractable P at 30 kg ha1 and 1 N ammonium acetate extractable K at 320 kg ha1 as determined by procedures described by Prasad (1998). During the rice season the experiment was laid out in a factorial randomized block design with the four combinations of puddling or no puddling and direct seeding or transplanting of rice. There were three replications and the plot size for rice was 20:0 10:0 m2 . During the succeeding wheat season each rice plot was divided into two sub-plots and wheat was broadcast with no tillage or drilled after tillage. In plots where puddling was not done, the soil was cultivated while it was dry. The plots were then filled with water and sprouted rice seeds were broadcast or rice seedlings were transplanted. Puddling was done by flooding the plots and rotovating followed by levelling. This operation was repeated three times. Transplanting or sprouted rice seed sowing was then done. The rice variety was Pusa 834 and three 25-dayold seedlings were transplanted at 20 cm inter-row and 10 cm intra-row spacing or 75 kg ha1 seed was broadcast. Plots for direct seeding of rice were prepared and sowing was done at the same time when nursery sowing was done, i.e. about a month in advance of date of transplanting. Direct seeding was thus done in the first week of June while transplanting was done in the first week of July. The water regime in all plots was maintained between saturation and flooding up to 5 cm standing water. The water applied in different treatments was measured with Parshall flume fixed at the start of the main channel of plots. Rice was harvested in the last week of October. Tillage for wheat involved two discings and levellings as soon as the field came to cultivation after rice harvest. Wheat was drilled with a seed drill in no-till or tilled plots the same day to avoid differences in yield due to date of sowing. Wheat variety used was HD 2329. Wheat was sown in the third week of November and harvested in the second week of April, the following year. Rice received 100 kg N as urea, 40 kg P2O5 as ordinary superphosphate, 40 kg K2O as muriate of potash and 25 kg zinc sulphate per hectare. Nitrogen was applied in two doses; half at sowing/transplanting and the other half at panicle initiation. Wheat received
S. Singh et al. / Soil & Tillage Research 61 (2001) 125–131
127
Table 1 Total monthly rainfall at New Delhi
100 kg N as urea, 40 kg P2O5 as ordinary superphospahte and 40 kg K2O as muriate of potash per hectare. Nitrogen was applied in two doses, half at sowing and the other half at first irrigation (25 days after sowing). Wheat received 3–5 irrigations.
Month
3. Results and discussion 3.1. Grain yield Although the crops were raised under irrigation natural rainfall still controls crop yields. In 1993– 1994 and 1994–1995 July rainfall was very good and it encouraged rapid vegetative growth, which finally showed up in grain yield (Table 1). In 1995–1996 July rainfall was much below the normal and rice crop, in general, was adversely affected. Furthermore, heavy rainfall in September, when the rice crop was at flowering stage adversely affected the crops. This explains why rice grain yield was the lowest in 1995– 1996. Wheat yield in 1994–1995 and 1995–1996 was also adversely affected by relatively more rain than in 1993–1994 in January, when the reproductive phase begins in the crop. Puddling significantly increased grain yield of rice as well as of the succeeding wheat crop (Table 2); the increase ranged from 0.7 to 1 t ha1 in rice and from 0.2 to 0.4 t ha1 in wheat. Thus total gain by puddling ranged from 0.9 to 1.4 t ha1 in rice–wheat cropping system. In an experiment at the International Rice
Total monthly rainfall (mm) 1993–1994
1994–1995
1995–1996
July August September October November December January February March April
305.0 160.8 227.0 0.0 0.0 0.0 10.4 9.2 8.8 4.0
450.6 171.1 3.4 0.0 0.0 0.0 66.6 22.0 20.6 0.0
70.6 432.2 184.4 0.0 0.0 1.8 80.4 10.2 5.4 0.0
Total
725.2
734.3
785.0
Research Institute, Philippines also irrigated rice yielded 7.9 t ha1 in a puddled soil but yielded only 3.6 t ha1 in a non-puddled soil (De Datta et al., 1973). The increase in productivity of rice–wheat cropping system by puddling may be due to better control of weeds (De Datta and Barker, 1978), maintenance of suitable water regime (Singh et al., 1995) and creation of anaerobic soil conditions (Ponnamperuma, 1972). Although a weed count was not made in the present study, there were lesser weeds in puddled plots than in unpuddled plots. Reddy and Hukkeri (1980a) also observed that increase in rice yield due to puddling was largely due to lesser weed growth due to puddling.
Table 2 Effect of puddling and method of seeding of rice on grain yield (t ha1) of rice and succeeding wheat Treatment
1993–1994
1994–1995
1995–1996
Rice
Wheat
Total
Rice
Wheat
Total
Rice
Wheat
Total
No puddling Direct seeding Transplanting
3.2 3.4
3.9 4.4
7.1 7.8
3.2 4.1
3.1 3.0
6.3 7.1
2.7 3.4
3.0 3.2
5.7 6.6
Mean
3.3
4.1
7.4
3.6
3.0
6.6
3.0
3.1
6.1
Puddling Direct seeding Transplanting
3.8 4.2
4.4 4.6
8.2 8.8
4.4 4.8
3.3 3.3
7.7 8.1
3.1 4.4
3.5 3.2
6.6 7.6
Mean
4.0
4.5
8.5
4.6
3.3
7.9
3.7
3.3
7.0
LSD ðP ¼ 0:05Þ for puddling LSD ðP ¼ 0:05Þ for puddling seeding
0.57 0.80
0.11 0.15
– –
0.88 1.25
0.29 0.42
– –
0.17 0.24
0.54 NS
– –
128
S. Singh et al. / Soil & Tillage Research 61 (2001) 125–131
3.2. Straw yield Puddling increased straw yield of rice (0.7– 1.7 t ha1) and of succeeding wheat (0.1–0.5 t ha1) significantly (Table 4). Thus total gain in straw yield by puddling in rice–wheat system ranged from 1.2 to 1.8 t ha1. Transplanting rice resulted in significantly more straw than direct seeded rice (Fig. 2). Like grain, the highest straw yield of rice and wheat was obtained when rice was transplanted on puddled soil and the lowest when rice was seeded directly on unpuddled soil. Transplanting of rice increased total straw yield of rice–wheat cropping system over direct seeded rice by 1.2–1.9 t ha1 on unpuddled soil and by 1.5– 2.3 t ha1 on puddled soil. Similarly puddling increased total straw yield of rice–wheat system over no puddling by 1.2–1.4 t ha1 when rice was transplanted and by 1.1–2.6 t ha1 when rice was direct seeded. Tillage for wheat increased straw yield over zero tillage in 2 out of 3 years; the increase ranged from 0.2 to 0.5 t ha1 (Table 3).
Fig. 1. Effect of method of seeding of rice on the grain yield (t ha1) of rice–wheat cropping system.
3.3. Water management
Method of rice seeding also significantly influenced grain yield of rice (Fig. 1). Transplanted rice yielded 0.2–1.3 t ha1 more grain than direct seeded rice. The highest grain yield for the rice–wheat cropping system was obtained when rice was transplanted on puddled soil; 0.4–1.0 t ha1 more than for direct seeded puddled rice, 1 t ha1 more than for transplanted unpuddled rice and 1.7–1.9 t ha1 more than for direct seeded unpuddled rice. Tillage also increased grain yield of wheat over that obtained with zero tillage by 0.4 t ha1 in the first year and 0.5 t ha1 in the second year. However, in the third year the effects of tillage on grain yield of wheat were not significant (Table 3).
Data on water requirement and water use efficiency (WUE) are given in Table 5. Puddling curtailed water requirement of rice by 75 mm ha mainly because of less percolation losses in puddled plots than in unpuddled plots. This resulted in higher WUE (2.8 kg grain mm ha1 water) with puddling as compared to without puddling (2.2 kg grain mm ha1 water). Method of rice seeding had no significant effect on water requirement of rice; however, transplanted rice required more water than direct seeded rice on unpuddled soil, whereas on puddled soil it was vice versa. It was due to the fact that rice was direct
Table 3 Effect of tillage in wheat on grain and straw yield (t ha1) Treatment
1993–1994
1994–1995
1995–1996
Grain
Straw
Total
Grain
Straw
Total
Grain
Straw
Total
Zero tillage Conventional tillage
4.2 4.6
6.3 6.8
10.5 11.4
3.6 4.1
4.3 4.6
7.9 8.7
3.2 3.3
4.8 5.0
8.0 8.3
LSD ðP ¼ 0:05Þ
0.17
0.25
–
0.09
0.17
–
NS
NS
–
S. Singh et al. / Soil & Tillage Research 61 (2001) 125–131
129
Table 4 Effect of puddling and method of seeding of rice on straw yield (t ha1) of rice and succeeding wheat Treatment
1993–1994
1994–1995
1995–1996
Rice
Wheat
Total
Rice
Wheat
Total
Rice
Wheat
Total
No puddling Direct seeding Transplanting
5.9 7.0
5.7 6.5
11.6 13.5
6.0 8.0
4.0 4.6
10.0 12.6
5.5 6.1
4.6 5.1
10.1 11.2
Mean
6.4
6.3
12.7
7.0
4.3
11.3
5.8
4.8
10.6
Puddling Direct seeding Transplanting
6.3 7.9
6.7 7.0
13.0 14.9
7.7 8.8
4.5 4.9
12.2 13.7
6.5 8.6
5.0 4.8
11.5 13.4
Mean
7.1
6.8
13.9
8.2
4.7
12.9
7.5
4.9
12.4
LSD ðP ¼ 0:05Þ for puddling LSD ðP ¼ 0:05Þ for puddling seeding
0.98 1.38
0.30 0.42
– –
1.34 1.99
0.24 0.34
– –
0.31 0.44
NS NS
– –
seeded on dry and unpuddled soil and required only 2–3 irrigations during seedling stage (30 days), whereas when rice was direct seeded on puddled soil it required irrigations on alternate days even during seedling stage. This could be mainly because when rice was direct seeded in unpuddled soils its roots went deeper in soil as in upland rice and could obtain water
from lower soil layers. On the other hand, root system in direct seeded puddled soil remained restricted to the surface layer only and thus could not obtain water from lower soil layers and called for frequent irrigation. However, WUE was always higher in transplanted rice than direct seeded rice mainly because of higher grain yield in the former than in the latter (Table 2). Our results are in conformity with those of De Datta et al. (1973) who reported that crop in puddled soil produced 9.0 kg grain mm ha1 water, while the crop on non-puddled soil produced only 8.3 kg grain mm ha1 water. Reddy and Hukkeri (1980b) also reported higher efficiency of irrigation water due to puddling. 3.4. Economics
Fig. 2. Effect of method of seeding of rice on the straw yield (t ha1) of rice–wheat cropping system.
Puddling increased gross income over no puddling by US $108 ha1 in rice and US $39 ha1 in wheat and reduced cost of rice cultivation by US $27 ha1 (Table 6). The growing of rice without puddling resulted in a net loss of US $29 ha1, whereas growing a rice crop on puddled soil gave a net return of US $106 ha1. Since the cost of cultivation of wheat was the same (US $290 ha1) after puddled and unpuddled rice, wheat after puddled rice gave US $39 ha1 more net return than wheat after unpuddled rice. Thus puddling increased net return of rice–wheat system by US $174 ha1. Transplanting of rice also increased gross return of both rice and succeeding wheat as compared to direct
130
S. Singh et al. / Soil & Tillage Research 61 (2001) 125–131
Table 5 Effect of puddling and method of seeding of rice on irrigation water requirement (IWR) and water use efficiency (WUE) of rice–wheat cropping system (mean over 3 years) Treatment
Rice
Wheat
Total
IWR (mm ha)
WUE (kg grain mm ha1 water)
IWR (mm ha)
WUE (kg grain mm ha1 water)
IWR (mm ha)
WUE (kg grain mm ha1 water)
No puddling Direct seeding Transplanting
1500 1575
2.0 2.2
400 400
8.2 8.7
1900 1975
3.3 3.6
Mean
1537
3.1
400
8.4
1937
3.4
Puddling Direct seeding Transplanting
1475 1450
2.6 3.1
400 400
9.2 9.2
1875 1850
4.0 4.4
Mean
1462
2.8
400
9.2
1862
4.2
Table 6 Effect of puddling and method of seeding of rice on economic return (US $ ha1) of rice–wheat cropping system (mean over 3 years of study)a Treatment
Rice
Wheat
Gross income
Cost of cultivation
No puddling Direct seeding Transplanting
428 514
516 485
Mean
471
Puddling Direct seeding Transplanting Mean
Net income
Total
Gross income
Cost of cultivation
Net income
Gross income
Cost of cultivation
Net cultivation
88 29
577 620
290 290
287 330
1005 1134
806 775
199 359
500
29
598
290
308
1069
790
279
528 631
471 476
57 155
647 647
290 290
357 357
1175 1278
761 766
414 512
579
473
106
647
290
357
1226
763
463
a Gross income was calculated on the basis of Government of India procurement price: rice grain @ US $117.5 t1, wheat grain @ US $137.5 t1 and prevailing price of straw @ US $1.25 t1 and wheat straw @ US $2.50 t1. Cost of cultivation was calculated on the basis of prevailing prices of different inputs.
seeding. The cost of cultivation of transplanted rice was less than direct seeded rice on unpuddled soil and more on puddled soil. This difference was due to heavy weed infestation in unpuddled direct seeded rice as compared to unpuddled transplanted rice. Puddling reduced weed population in rice and hence transplanting on puddled soil involved no extra cost of weed control. The net return from rice–wheat cropping system was the highest when rice was transplanted on puddled soil and the lowest when rice was directly seeded on unpuddled soil. Transplanting of rice increased net return of rice–wheat system by US $100 ha1 with puddling and by US $152 ha1 with-
out puddling. Similarly, puddling increased net return of rice–wheat cropping system by US $200 ha1 when rice was direct seeded and US $148 ha1 when rice was transplanted.
4. Conclusions Our results show that rice yields are the highest when it is transplanted on puddled land. Even if rice is seeded directly it should be seeded on puddled land. Again for high yields wheat after rice should be sown after conventional tillage.
S. Singh et al. / Soil & Tillage Research 61 (2001) 125–131
References Bodman, G.B., Rubin, J., 1948. Soil puddling. Soil Sci. Soc. Am. Proc. 13, 27–36. De Datta, S.K., Barker, B., 1978. Land preparation for rice soil. In: Soil and Rice. International Rice Research Institute, Los Banos, Philippines, pp. 623–648. De Datta, S.K., Krupp, H.K., Alvarez, E.I., Modgal, S.C., 1973. Water management practices in flooded tropical rice. In: Water Management in Philippines Irrigation Systems: Research and Operations. International Rice Research Institute, Los Banos, Philippines, pp. 1–18. Kumar, P., Josh, P.K., Johansen, C., Asokan, M., 1998. Suitability of rice–wheat based cropping system. In: India — Socioeconomic and Policy Issues. Economic and Political Weekly 33, September 26, pp. 152–158.
131
Ponnamperuma, F.N., 1972. The chemistry of submerged soils. Adv. Agron. 29, 29–96. Prasad, R., 1998. A Practical Manual for Soil Fertility. Division of Agronomy, Indian Agricultural Research Institute, New Delhi. Reddy, S.R., Hukkeri, S.B., 1980a. Increasing effectiveness of fertilizers through weed control in direct seeded irrigated rice. Fert. News 25, 30–33. Reddy, S.R., Hukkeri, S.B., 1980b. Effect of tillage practices on irrigation requirement, weed control and yield of lowland rice. Soil Till. Res. 3, 147–158. Sharma, P.K., De Datta, S.K., 1986. Physical properties and processes of puddled rice soils. Adv. Soil Sci. 5, 139–178. Singh, R., Gajri, P.R., Gill, K.S., Khera, R., 1995. Puddling intensity and nitrogen use efficiency of rice (Oryza sativa) on a sandy loam soil of Punjab. Indian J. Agric. Sci. 65, 749–751.