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Soil & Water

Saving of Water and Labor in a Rice–Wheat System with No-Tillage and Direct Seeding Technologies

^a International Rice Research Institute (IRRI), India Office, New Delhi 110012, India
^b Rice–Wheat Consortium for IGP, CIMMYT-RWC, CG Block, NASC Complex, DPS Marg, Pusa Campus, New Delhi 110012, India
^c Dep. of Crop and Soil Sciences, Cornell Univ., Ithaca 14853, NY
^d IRRI, Los Baños, Manila, the Philippines

^* Corresponding author (J.K.Ladha{at}cgiar.org)

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Conventional tillage and crop establishment methods such as puddled transplanting in the rice–wheat (Oryza sativa L.–Triticum aestivum L.) system in the Indo-Gangetic Plains (IGP) require a large amount of water and labor, both of which are increasingly becoming scarce and expensive. We attempted to evaluate alternatives that would require smaller amounts of these two inputs. A field experiment was conducted in the IGP for 2 yr to evaluate various tillage and crop establishment systems for their efficiency in labor, water, and energy use and economic profitability. The yields of rice in the conventional puddled transplanting and direct-seeding on puddled or nonpuddled (no-tillage) flat bed systems were equal. Yields of wheat following either the puddled-transplanted or no-tillage direct-seeded rice were also equal. Normally, puddled transplanting required 35 to 40% more irrigation water than no-tillage direct-seeded rice. Compared with conventional puddled transplanting, direct seeding of rice on raised beds had a 13 to 23% savings of irrigation water, but with an associated yield loss of 14 to 25%. Nevertheless, water use efficiency (WUE) in the rice–wheat system was higher with direct-seeded rice (0.45 g L^–1) than with transplanted rice (0.37–0.43 g L^–1). In Year 1, no-tillage rice–wheat had a higher net return than the conventional system, whereas in Year 2 the net returns were equal. The study showed that the conventional practice of puddled transplanting could be replaced with no-tillage-based crop establishment methods to save water and labor. However, the occurrence and distribution of rainfall during the cropping season had considerable influence on the savings in irrigation water.

Abbreviations: IGP, Indo-Gangetic Plains • LCC, leaf color chart • WUE, water use efficiency

Received for publication August 6, 2006.

Saving of Water and Labor in a Rice–Wheat System with No-Tillage and Direct Seeding Technologies

^a International Rice Research Institute (IRRI), India Office, New Delhi 110012, India
^b Rice–Wheat Consortium for IGP, CIMMYT-RWC, CG Block, NASC Complex, DPS Marg, Pusa Campus, New Delhi 110012, India
^c Dep. of Crop and Soil Sciences, Cornell Univ., Ithaca 14853, NY
^d IRRI, Los Baños, Manila, the Philippines

^* Corresponding author (J.K.Ladha{at}cgiar.org)

Received for publication August 6, 2006.
Conventional tillage and crop establishment methods such as puddled transplanting in the rice–wheat (Oryza sativa L.–Triticum aestivum L.) system in the Indo-Gangetic Plains (IGP) require a large amount of water and labor, both of which are increasingly becoming scarce and expensive. We attempted to evaluate alternatives that would require smaller amounts of these two inputs. A field experiment was conducted in the IGP for 2 yr to evaluate various tillage and crop establishment systems for their efficiency in labor, water, and energy use and economic profitability. The yields of rice in the conventional puddled transplanting and direct-seeding on puddled or nonpuddled (no-tillage) flat bed systems were equal. Yields of wheat following either the puddled-transplanted or no-tillage direct-seeded rice were also equal. Normally, puddled transplanting required 35 to 40% more irrigation water than no-tillage direct-seeded rice. Compared with conventional puddled transplanting, direct seeding of rice on raised beds had a 13 to 23% savings of irrigation water, but with an associated yield loss of 14 to 25%. Nevertheless, water use efficiency (WUE) in the rice–wheat system was higher with direct-seeded rice (0.45 g L^–1) than with transplanted rice (0.37–0.43 g L^–1). In Year 1, no-tillage rice–wheat had a higher net return than the conventional system, whereas in Year 2 the net returns were equal. The study showed that the conventional practice of puddled transplanting could be replaced with no-tillage-based crop establishment methods to save water and labor. However, the occurrence and distribution of rainfall during the cropping season had considerable influence on the savings in irrigation water.

Abbreviations: IGP, Indo-Gangetic Plains • LCC, leaf color chart • WUE, water use efficiency

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
THE RICE–WHEAT ROTATION is one of the major agricultural production systems in Asia, occupying about 18 million ha, of which 13.5 million ha are in the Indo-Gangetic Plains (IGP) of Bangladesh, India, Nepal, and Pakistan (Ladha et al., 2000; Dawe et al., 2004). The intensively cultivated irrigated rice–wheat system is fundamental to employment, income, and livelihoods for hundreds of millions of rural and urban poor of South Asia. In the last few decades, annual increases in growth rates for food grain production (wheat 3.0%, rice 2.3%) in the IGP have kept pace with population growth. But evidence is now appearing that rice–wheat system productivity is plateauing because of a fatigued natural resource base (Ladha et al., 2003). Thus, the region's food security is threatened by the emerging challenges of post Green Revolution agriculture, and the rising population.

Farmers in this region usually grow rice in the wet (monsoon) season, followed by wheat in the dry (winter) season. Rice and wheat crops have contrasting edaphic requirements and differing tillage and agronomic practices. For rice, intensive wet tillage (puddling) is practiced, whereas wheat is grown as a dryland crop. The drastically different seedbed requirements for rice and wheat create problems in tillage, timeliness of wheat seeding, maintenance of soil structure, and management of irrigation, weeds and other pests, fertilizers, and crop residues. A short turnaround time between rice and wheat is required to prevent delayed wheat planting that can result in yield losses of 35 (northwestern IGP) to 60 kg d^–1 ha^–1 (eastern IGP) (Pathak et al., 2003). However, delays do occur because farmers insist on excessive tillage before wheat planting and the growing of a medium-duration (140-d) basmatic rice variety. Moreover, seasonality of labor demand and the seasonal migratory nature of the labor market are increasingly becoming a serious concern for the timely planting of crops.

In the IGP, as well as in many other parts of Asia, water is increasingly becoming scarce. Per capita availability of water has declined in many Asian countries by 40 to 60% between 1955 and 1990 (Gleik, 1993). Agriculture's share of freshwater supplies is likely to decline by 8 to 10% because of increasing competition from the urban and industrial sectors (Seckler et al., 1998; Toung and Bhuiyan, 1994). Poor-quality irrigation systems and greater reliance on groundwater have led to water table decline of 0.1 to 1.0 m yr^–1 in parts of the IGP, resulting in a scarcity and higher cost of pumping water (Gill, 1994; Harrington et al., 1993; Sharma et al., 1994; Sondhi et al., 1994).

The growing labor and water shortages are likely to adversely affect the productivity of the rice–wheat system (Ladha et al., 2003). One way to reduce water demand is to grow direct-seeded rice instead of the conventional puddled transplanted rice (Bhuiyan et al., 1995; Cabangon et al., 2002). Dry seeding of rice with subsequent aerobic soil conditions avoids water application for puddling and maintenance of submerged soil conditions, and thus reduces the overall water demand (Bouman, 2001; Sharma et al., 2002). Another way to save water is to grow rice in raised beds, as Borrel et al. (1997) observed that the raised-bed system saved 16 to 43% water compared with puddled transplanted rice, though at the expense of yield. Similarly, a yield reduction of >15% was reported when rice was grown on raised beds vis-à-vis the puddled-transplanted system (Sharma et al., 2003; Vories et al., 2002). Intermittent irrigation and mid-season drying of soil instead of continuous submergence as used in the conventional puddled-transplanted system could be another option for saving water.

Compared with rice, wheat has a much lower water demand. Rice consumes about 80% of the total water applied in the rice–wheat system. Therefore, much water could be saved if tillage and crop establishment practices of wheat were adopted in rice. However, the extension of tillage and crop establishment practices followed in wheat to rice without a yield penalty has always been a major challenge for researchers. Minimum tillage or no-tillage is becoming an increasingly accepted management technology in parts of the IGP (Hobbs and Gupta, 2002; Singh and Ladha, 2004). Tillage operations performed and establishment methods followed for growing rice should complement those practiced for growing wheat and vice versa. It is the overall system productivity that should be considered while judging the suitability of a practice, and not just the individual crop productivity. Although it is often claimed that reduced-tillage operations with alternative crop establishment methods such as direct seeding on flat land and raised beds can result in significant water savings (Gupta et al., 2003), systematic studies evaluating the effects of these practices on yield, soil fertility, and water requirement of the rice–wheat system are lacking. The objectives of our study were to evaluate the effects of various tillage and seeding methods on productivity, irrigation requirement and WUE, and net return of the rice–wheat system of the IGP.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Experimental Site
The experiment was conducted at the research farm (29°01' N, 77°45' E, and 237 m above mean sea level) of Sardar Vallabh Bhai Patel University of Agriculture & Technology, Uttar Pradesh, India, during 2002–2004. The climate of the area is semiarid, with an average annual rainfall of 800 mm (75–80% of which is received during July to September), minimum temperature of 0 to 4°C in January, maximum temperature of 41 to 45°C in June, and relative humidity of 67 to 83% throughout the year. The experimental soil (0–15 cm) was silty loam in texture, with a bulk density of 1.42 Mg m^–3, weighted mean diameter of soil aggregates = 0.71 mm, pH 8.1, EC (saturation extract) = 0.4 dS m^–1, total C = 8.3 g kg^–1, total N = 0.88 g kg^–1, Olsen P = 25 mg kg^–1, and 1 M NH₄OAC extractable K = 121 mg kg^–1. The soil retained 18 and 7% water (mass basis) at 30 and 1500 kPa water potential.

Experimental Design and Treatments
Six treatments (T1 to T6) involving three tillage and two rice establishment methods were evaluated in the rice–wheat rotation during 2002–2003 (Year 1) and 2003–2004 (Year 2) using a randomized complete block design with three replications. The total plot area for each treatment was 100.5 m² (15.0 x 6.7 m). The tillage methods were (i) conventional puddling for rice and conventional tillage for wheat, (ii) raised beds with reduced-tillage for rice and wheat, and (iii) flat land with no-tillage for rice and wheat. The crop seeding methods included (i) conventional puddled transplanting of rice, (ii) direct seeding of rice, and (iii) no till seeding of both wheat and rice. The details of practices followed in various treatments are described below and summarized in Table 1.

View larger version (23K): [in this window] [in a new window]   Fig. 1. Method of rice establishment in (a) transplanted on flat land in puddled and no-tillage conditions, (b) raised-bed system, and (c) no-till direct-seeded conditions.

Treatment 3: Direct Drill-Seeded Rice and Wheat on Raised Beds after Reduced Tillage
Soil was tilled by two harrowings and two plowings followed by one field leveling with a wooden plank, and the raised beds were made using a tractor-drawn bed planter. The configuration of the beds is shown in Fig. 1b. The beds were 37 cm wide at the top and 15 cm in height, and separated by furrows 30 cm wide. Two rows of rice were direct-seeded on each raised bed at 20-cm row-to-row spacing. The raised beds were seeded using a bed planter, which placed seeds and fertilizer simultaneously. The first irrigation was applied at 1 day after seeding (DAS), followed by daily irrigations for 2 wk after germination to maintain soil saturation. The irrigations were applied to completely fill the furrows. Subsequent irrigations (completely filling the furrows) were given at the appearance of hairline cracks at the soil surface at the bottom of the furrow. After rice, wheat was seeded directly after reshaping the beds using a bed planter. In 2002, the wheat was irrigated at the Z20, Z29, Z36, and Z83 growth stages, whereas in 2003, irrigation was applied at the Z20, Z29, Z36, Z55, Z83, and Z87 stages. The irrigation treatments were applied to completely fill the furrows.

Treatment 4: Transplanted Rice on Raised Beds and Drill-Seeded Wheat after Reduced Tillage
Beds were prepared as in T3, followed by transplanting of one 21-d-old seedling per hill in two rows at 20-cm spacing on the raised beds (Fig. 1b). Plant-to-plant spacing was 12 cm to maintain the population equal to that of the conventional transplanted method. The plots were kept flooded for 2 wk after seeding and subsequent irrigations were applied to completely fill the furrows at the appearance of hairline cracks at the soil surface at the bottom of the furrow. After rice, wheat was seeded directly after reshaping the beds using a bed planter. The same number and timing of irrigation events were applied as in T3.

Treatment 5: No-Till Drill-Seeded Rice and No-Till Wheat
Rice was direct-seeded in flat plots at 20-cm row spacing using a no-till press drill with dry-fertilizer attachment. The seeding was done on the same day when the nursery for transplanted rice was seeded. The first irrigation was applied immediately after seeding, and the plots were irrigated daily for 2 wk after germination to maintain saturation. Subsequent irrigations were applied at the appearance of hairline cracks at the soil surface. Wheat was seeded using a no-till press drill with dry-fertilizer attachment. As in T2, four irrigations in 2002 and six irrigations in 2003 were applied to the crop.

Treatment 6: No-Till Transplanted Rice and No-Till Drill-Seeded Wheat
For rice, slits were opened using a no-till drill in dry conditions. The plots were then flooded and transplanting was done in the open slits with 20- by 20-cm spacing. The plots were irrigated daily for 2 wk after transplanting, and subsequent irrigations were applied at the appearance of hairline cracks at the soil surface. Wheat was seeded using a no-till press drill with dry-fertilizer attachment. The crop received irrigations as in T2.

Out of these six treatments, the conventional practice (T1) is currently used in about 10 million ha in the IGP. The practice of no-tillage in wheat is gaining popularity and is now practiced in about 2.0 million ha (R.K. Gupta, unpublished data, 2006). Farmers in north India also occasionally follow the practice of midseason drying (T2) as the cost of irrigation is escalating due to increasing price of diesel.

Seeding and Seed Rate
‘NDR 359’ rice was seeded on 7 and 3 June in direct-seeded plots, whereas transplanting was done on 28 and 24 June in 2002 and 2003, respectively. Rice was seeded in flat beds as well as in raised beds after seed priming (soaking seeds in water for 12 h followed by air drying). A seeding rate of 40 and 30 kg ha^–1 was used for direct-seeded rice on flat and raised beds, respectively. ‘PBW 343’ wheat was seeded on 2 and 7 Nov. 2002 and 2003, respectively. A seeding rate of 90 kg ha^–1 was used in treatments where wheat was seeded on beds, and 120 kg ha^–1 was used in the rest of the treatments. The press drill with dry-fertilizer attachment was calibrated every time before seeding to adjust the seeding rate.

Water Application and Measurements
Irrigation water was applied using polyvinyl chloride pipes of 10-cm diameter and the amount of water applied to each plot was measured using a water meter (Dasmesh Co., India). The quantity of water applied and the depth of irrigation were computed using the following equations:

[1]

[2]

where F is flow rate (L s^–1), t is time (s) taken during each irrigation, and A is area of the plot (m²).

Rainfall data were recorded using a rain gauge. The total amount of water applied was computed as the sum of water received through irrigations and rainfall. The soil water tension was measured at the 15-cm depth in all the plots using mercury tensiometers. In the case of raised beds, tensiometers were placed in the center of the beds. These data were used to compute the soil matric suction (_m, kPa) using the following formula:

[3]

where H = height of mercury column from a reference point (cm), R = height of the mercury reservoir (reference point) from the soil surface (cm), and D = depth of soil at which the tensiometer is placed (cm).

The WUE (g grains L^–1 of water) was computed as follows (Prihar and Sandhu, 1987):

[4]

Fertilizer Application
All plots received 120 kg N, 26 kg P, 50 kg K, and 8.75 kg Zn ha^–1 in rice and wheat. Although K and Zn fertilizers were broadcast for rice, N and P fertilizers were placed at the 10-cm depth using a no-till drill attached with a bed planter at the time of seeding except in puddled transplanting (T1), where they were placed at the 10-cm depth manually at the center of each cluster of four hills. An additional dose of 30 kg N ha^–1 was applied to rice when the leaf color in individual plot was below the leaf color chart (LCC) critical value of 4. The color of leaves was monitored every week by LCC in individual plots separately, and when the color of leaves was below 4, N was applied in that plot. For LCC-based N application, the critical value of 4 was based on the findings of Shukla et al. (2004) for cultivar NDR 359 of rice. For wheat, all the fertilizers were applied basally using press drill with dry-fertilizer attachment.

Weed Management
Weeds that germinated before the seeding of rice and wheat in no-till plots were killed by spraying glyphosate at 900 g a.i. ha^–1. The plots were then kept weed-free throughout the growing season. Anilophos at 375 g a.i. ha^–1 at 2 d after transplanting (DAT) in the case of transplanted rice and pretilachlor plus safener at 480 g a.i. ha^–1 at 3 DAS in direct-seeded rice were applied to control grass weeds, followed by a spray application of chlorimuron ethyl + metsulfuron methyl (Almix, DuPont, Wilmington, DE) at 4 g a.i. ha^–1 at 21 DAS for broadleaf weeds. Additionally, two hand weedings in transplanted rice and three in direct-seeded rice were also required to keep the plots weed-free. For wheat, grassy weeds were controlled by spraying sulfosulfuron at 35 g a.i. ha^–1 at 21 DAS, and broadleaf weeds were controlled using 2,4-D at 500 g a.i. ha^–1 at 35 DAS, followed by one hand weeding.

Harvesting
At maturity, rice and wheat were harvested manually at 15 cm above ground level. Grain and straw yields were determined from an area of 70.2 m² in flat beds and 69.7 m² in raised beds located in the center of each plot. The grains were threshed using a plot thresher, dried in a batch grain dryer, and weighed. Grain moisture was determined immediately after weighing. Grain yields of rice and wheat were reported at 140 and 120 g water content kg^–1, respectively. Straw weight was determined after oven-drying at 70°C to constant weight and expressed on an oven dry-weight basis.

Soil and Plant Sampling and Analysis
Soil samples were collected at the start of the experiment from the 0- to 15-cm soil depth using an auger of 5-cm diameter. Each sample was a composite from three locations within a plot. The freshly collected soil samples were mixed thoroughly, air-dried, crushed to pass through a 2-mm sieve, and stored in sealed plastic jars before analysis. Olsen-P (0.5 M NaHCO₃ extractable) and NH₄OAc-extractable K were analyzed using the methods described by Olsen et al. (1954) and Page et al. (1982), respectively. Soil organic C was analyzed by Walkley and Black method (Page et al., 1982). The bulk density of the soil was determined from core-ring samples taken at 0- to 15-cm depth at seeding or transplanting. Soil samples were analyzed for particle size distribution (Bouyoucos, 1962), mean weight diameter of peds (Yoder, 1936), and water retention (Richards, 1965).

Grain and straw samples of rice and wheat collected from each plot were dried at 70°C in a hot-air oven. The dried samples were ground in a stainless steel Wiley Mill and N contents in leaf, grain, and straw were determined by digesting the samples in sulfuric acid (H₂SO₄), followed by analysis of total N by the Kjeldahl method (Page et al., 1982) using a Kjeltec autoanalyzer.

Labor Use
Human labor use for tillage, seeding, irrigation, fertilizer and pesticide application, weeding, and harvesting in rice and wheat were measured in this study. Time (h) required to complete one field operation in a particular treatment was recorded and was expressed as person-day ha^–1, considering 8 h to be equivalent to 1 person-day. Similarly, time (h) required by a tractor-drawn machine to complete a field operation such as tillage, seeding, fertilizer application, and harvesting was recorded and expressed as h ha^–1. Time (h) required to irrigate a particular plot and consumption of diesel (1 h^–1) by the pump was also recorded. Labor and machine requirements have a component of site-specificity as they depend on the existing soil, crop and climatic conditions, and the efficiency and skill of operation. For example, a heavy soil will require more time to be plowed compared with a light soil. Similarly, time required for irrigation largely depends on the depth of ground water, the capacity of the pump, and method of irrigation. The data on labor use presented in this paper pertains to a silty loam soil in a semiarid climate and water was pumped from a depth of 50 m with a 10 horse power pump, and irrigation was given by the surface-flooding method. In this study, only one measurement per treatment was taken, and no distinction was made between the skilled and unskilled laborers.

Economic Analysis
The cost of cultivation was calculated by taking into account costs of seed, fertilizers, biocide, and the hiring charges of human labor (U.S. $2.30 d^–1) and machines (U.S. $5.6 h^–1) for land preparation, irrigation, fertilizer application, plant protection, harvesting, and threshing, and the time required per hectare to complete an individual field operation. Cost of irrigation was calculated by multiplying time (h) required to irrigate a particular plot, consumption of diesel by the pump (1 h^–1) and cost of diesel (U.S. $0.73 l^–1). The prices of human and machine labor, and diesel are their current prices in north India collected by market survey. Gross income was the minimum support price offered by the Government of India for rice (U.S. $126.09 Mg^–1) and wheat (U.S. $124.78 Mg^–1). Net income of the farmers was calculated as the difference between gross income and total cost. System productivity was calculated by adding the grain yield of rice and wheat in each year.

Data Analysis
All the data on yield and yield parameters of rice and wheat, WUE, economics, and nutrient uptake were analyzed with IRRISTAT for Windows for one-way ANOVA with partitioning of treatments by linear contrast (IRRI, 2005). Duncan's multiple range test was used at the P < 0.05 level of probability to test the differences between the treatment means. Linear contrasts were used to compare single or multiple treatments against one another.

	RESULTS AND DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Rice, Wheat, and System Productivity
Rice
The various tillage and crop establishment methods had a significant effect on rice yield in both years. Yields were similar when rice was conventionally transplanted (T1), direct drill-seeded after no-tillage (T5), and transplanted in slits after no-tillage (T6) (Table 2). This indicated that puddling of soil, for which normally a large amount of water and labor are required, can be avoided without any yield penalty in rice. Mid-season drying after the maximum tillering stage (T2) had a lower yield in 2002 than transplanted rice after conventional puddling (T1) and direct drill-seeded rice after no-tillage (T5). Reducing the number of irrigations in 2003 did not affect the rice grain yield negatively because adequate precipitation was received. As a result, this treatment (T2) had a yield similar to that of T1, T5, and T6. Rice either direct drill-seeded (T3 in 2003) or transplanted (T4 in 2002) on beds yielded 8 to 25% lower than conventional puddled transplanting (T1). Partitioning of treatments using linear contrast showed that conventional tillage treatments (T1, T2) gave higher rice yields than the raised bed and no tillage treatments (T3–T6) in 2003, whereas no tillage treatments (T5, T6) gave higher yields than the raised bed treatments (T3, T4) regardless of seeding method in both years (Table 2). Transplanted rice on beds (T4) apparently suffered from more water stress compared with flat land, resulting in lower yields. Lower panicle number (Table 3) and poor tillering (data not shown) were also recorded in this treatment. Several researchers have shown that moisture stress at panicle initiation and flowering stages could lead to yield loss because of reduction in number of grains per panicle and spikelet sterility (Lu et al., 2001; Nieuwenhuis et al., 2002; Belder et al., 2002). However, despite the higher panicle number (Table 3) in the direct-seeded no-tilled flat land (T5) than that of puddled-transplanted conditions (T1), rice yields were equal in both years (Table 2). This was due to higher sterility nullifying the advantage of higher panicle number in T5. Comparison of transplanting (T4, T6) and direct seeding (T3, T5) showed that rice yield was higher in the former in 2003. There was a significant interaction between tillage and seeding in 2002 only (Table 2).

Water Application and Use Efficiency
Rice
The irrigation water application was 38% higher in Year 1 than Year 2 (Table 5) because of less rainfall and poorer distribution pattern of rain (Fig. 2 ). Drought occurred early in the season of Year 1, which adversely affected the growth of rice seedlings. Transplanted rice used the highest amount of water in all tillage treatments (T1, T4, and T5) in both years (Table 5). Mid-season drying after puddled-transplanting (T2) had 15 to 22% less water applied than conventional puddle-transplanting (T1). Direct seeding of rice on flat land and raised beds (T3, T5) resulted in 13 to 23% less water application than in conventional puddled systems (T1). Table 6 shows the number of days when matric suction values were > 10 kPa in both years. It was observed that the matric suction values at a given time were higher on raised beds than on flat land except in the treatment with intensive drying (T2).

View this table: [in this window] [in a new window]   Table 5. Water application and water use efficiency in rice and wheat with various tillage and seeding treatments.

View larger version (17K): [in this window] [in a new window]   Fig. 2. Rainfall pattern during rice seasons in 2002 and 2003.

Rice–Wheat System
Analysis of variance showed significant treatment effects on WUE of a rice–wheat system (Table 5). Compared with the conventional tillage systems (T1), WUE was improved in the T2 treatment where mid-season drying was imposed on the rice and the subsequent wheat was planted no-till. Over all, both systems had similar crop yields (Table 2), but the T2 system used 15 to 20% less water. The ANOVA with partitioning of treatments showed a significant effect of seeding methods (T4 and T6 vs. T3 and T5) on WUE in Year 1 but not in Year 2. In addition, WUE was greater in no-tillage systems compared with raised bed systems (T3 and T4 vs. T5 and T6) in Year 2 but not in Year 1 (Table 5).

Direct seeding into no-till (T5) and raised beds (T3) increased WUE over conventional tillage (T1) in Year 1 but not in Year 2. Less water was applied to both the T3 and T5 treatments compared with T1, but there was no system yield difference in Year 1 (Table 2). In Year 2, both T3 and T5 had lower yields than T1. Transplanting rice into no-till (T6) and raised beds (T4) also required less water than the conventional T1 treatment, though the savings were not as great as in direct seeding systems, but the WUE was not improved of T1. In no-tillage systems, direct seeding (T5) saved about 17 to 18% and transplanting (T6) about 2 to 3% irrigation water on a system basis compared with conventional puddled transplanted rice (T1). With raised beds, water savings was 15 to 23% with direct-seeding (T3) and 5 to 12% with transplanted rice–wheat (T4) (Table 5).

Labor Use
Direct drill-seeded rice on raised beds (T3) had the highest machine labor requirement (14.3 tractor h ha^–1) followed by transplanted rice either on raised beds (T4) or after conventional puddling (T1) (Table 7). No-till rice either direct-seeded (T5) or transplanted (T6) had the lower machine labor requirements. Conventionally-tilled wheat (T1) had the highest machine labor requirement (12 tractor h ha^–1), whereas all other treatments had a machine labor requirement of about 6 tractor h ha^–1 as they were seeded using the no-till drill.

Economic Analysis
The net returns of rice were higher in Year 2 than in Year 1 largely because of more rainfall resulting in a lower cost of irrigation in Year 2 (Table 8). The largest financial benefit (U.S. $139, difference between the years) was for puddled transplanted rice (T1), followed by the no-tillage system (U.S. $30 in T5) and bed-planting system (U.S. $10 in T3). In wheat, the returns were higher in Year 1 than in Year 2 largely because of the differences in the amount of water applied. On a system basis, the returns were higher in T3 and T5 in Year 1, and in T1 in Year 2.

	CONCLUSIONS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Conventional practices of puddled transplanting in rice and extensive tillage in wheat require a large amount of water and labor. The emerging shortages and increasing costs of water and labor will therefore force a change in the way farmers grow these crops. An extented turnaround time between rice and wheat delays wheat planting that can result in yield losses. In addition, many farmers tend to transplant rice during the hot, high water evaporative demand months of May and June. No-tillage can allow timely seeding of wheat immediately after rice harvest. This would also enable farmers to delay rice seeding until end of June when the monsoon season starts, thereby reducing the irrigation application in rice planting. But there is grower apprehension that planting of rice in May will result in more yield compared to planting in July. However, simulation modeling using CERES-Rice has shown that planting of rice between April 20 and July 20 had similar potential yield (Pathak et al., unpublished data, 2005). Therefore, delaying rice planting up to 20 July may not affect yield potential.

This 2-yr study showed that with no-tillage and direct seeding, efficiencies of water and labor use, as well as net income, were greater than in the conventional farmers' practices. The water-saving feature of direct seeding is largely attributed to the avoidance of puddling used in transplanted rice. However, savings in irrigation largely depended on the occurrence and distribution of rainfall during the crop growing period. Therefore, more efforts will be needed to evaluate and improve the technologies on a site- and season-specific basis. Shifting from conventional tillage practice to no-till system may cause changes in soil properties, microflora, microfauna, and weed flora affecting long-term crop productivity and input use efficiency. Therefore, long-term changes in the crop performance, input efficiencies, and weed flora should be monitored to achieve a paradigm shift in farmers' practices. Appropriate integration of crop residue in no-tillage rice–wheat systems is another crucial issue which needs to be addressed. Therefore, we need to develop cost effective and profitable residue management practices which will attract the farmers for adoption. It is also important that small-scale farmers be trained and have access to these technologies.

	REFERENCES

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 

• Belder, P., B.A.M. Bouman, and L. Spiertz. Guoan Lu, and E.J.P. Quilang. 2002. Water use of alternately submerged and non-submerged irrigated lowland rice. 51–61. In B.A.M. Bouman et al. (ed.) Water-wise rice production. IRRI, Los Baños, the Philippines.
• Bhuiyan, S.I., M.A. Sattar, and M.A.K. Khan. 1995. Improving water use efficiency in rice irrigation through wet seeding. Irrig. Sci. 16:1–8.
• Borrel, A.K., A.L. Garside, and S. Fukai. 1997. Improving efficiency of water for irrigated rice in semi-arid tropical environment. Field Crops Res. 52:231–248.
• Bouman, B.A.M. 2001. Coping with the water crisis: Water management strategies in rice production. Paper presented at the International Symposium on Sustainable Soil and Water Resources Management. 30–31 May 2001. Diliman, Quezon City, the Philippines.
• Bouyoucos, G.J. 1962. Hydrometer method improved for making particle size analysis of soils. Agron. J. 54:464–465.[Abstract/Free Full Text]
• Cabangon, R.J., T.P. Tuong, and N.B. Abdullah. 2002. Comparing water input and water use efficiency of transplanted and direct-seeded rice production systems. Agric. Water Manage. 57:11–13.
• Counce, P.A., T.C. Keisling, and A.J. Mitchell. 2000. A uniform, objective, and adaptive system for expressing rice development. Crop Sci. 40:436–443.[Abstract/Free Full Text]
• Dawe, D., S. Frolking, and C. Li. 2004. Trends in rice–wheat area in China. Field Crops Res. 87:89–95.
• Gill, K.S. 1994. Sustainability issues related to rice–wheat production system. p. 30–61. In R.S. Paroda et al. (ed.) Sustainability of rice–wheat production systems in Asia. FAO, Bangkok, Thailand.
• Gleik, P.H. (ed.). 1993. Water crisis: A guide to the world's fresh water resources. Pacific Institute for Studies in Development, Environment and Security. Stockholm Environment Institute. Oxford Univ. Press, New York.
• Gupta, R.K., P.R. Hobbs, J. Jiaguo, and J.K. Ladha. 2003. Sustainability of post-Green revolution agriculture. 1–25. In J.K. Ladha et al. (ed.) Improving the productivity and sustainability of rice–wheat systems: Issues and impacts. ASA Spec. Publ. 65. ASA, CSSA, and SSSA, Madison, WI.
• Harrington, L.W., S. Fujisaka, M.L. Morris, P.R. Hobbs, H.C. Sharma, R.P. Singh, M.K. Choudhary, and S.D. Dhiman. 1993. Wheat and rice in Karnal and Kurukshetra districts, Haryana, India: Farmers' practices, problems and an agenda for action. ICAR, HAU, CIMMYT, Mexico, and IRRI, Los Baños, the Philippines.
• Hobbs, P.R., and R.K. Gupta. 2002. Rice–wheat cropping systems in the Indo-Gangetic plains: Issues of water productivity in resource-conserving technologies. Water Productivity Workshop, 12–14 Nov. 2001. Int. Water Management Inst., Colombo, Sri Lanka.
• IRRI. 2005. IRRISTAT for Windows: A statistical package for analysis of data [CD-ROM]. IRRI, Manila, the Philippines.
• Ladha, J.K., K.S. Fischer, M. Hossain, P.R. Hobbs, and B. Hardy. 2000. Improving the productivity of rice–wheat systems of the Indo-Gangetic Plains: A synthesis of NARS-IRRI partnership research. IRRI Discussion Paper No. 40. IRRI, Los Baños, the Philippines.
• Ladha, J.K., H. Pathak, A.T. Padre, D. Dawe, and R.K. Gupta. 2003. Productivity trends in intensive rice–wheat cropping systems in Asia. 45–76. In J.K. Ladha et al. (ed.) Improving the productivity and sustainability of rice–wheat systems: Issues and impacts. ASA Spec. Publ. 65. ASA, CSSA, and SSSA, Madison, WI.
• Lu, J., T. Hirasawa, and J. Lu. 2001. Study on intermittent irrigation for paddy rice: I. Water use efficiency. Pedosphere 11:49–56.
• Nieuwenhuis, J., B.A.M. Bouman, and A. Castaneda. 2002. Crop-water responses of aerobically grown rice: Preliminary results of pot experiments. p. 177–185. In B.A.M. Bouman et al. (ed.) Water-wise rice production. IRRI, Los Baños, the Philippines.
• Olsen, S.R., C.V. Cole, F.S. Watanabe, and L.A. Dean. 1954. Estimation of available phosphorus in soils by extraction with sodium bicarbonate. USDA Circ. 939. U.S. Gov. Print. Office, Washington, DC.
• Page, A.L., R.H. Miller, and D.R. Keeney (ed.). 1982. Methods of soil analysis. Part 2. Chemical and microbiological properties. 2nd ed. Agron. Monogr. 9. ASA, CSSA, and SSSA, Madison, WI.
• Pathak, H., J.K. Ladha, P.K. Aggarwal, S. Peng, S. Das, Y. Singh, B. Singh, S.K. Kamra, B. Mishra, A.S.R.A.S. Sastri, H.P. Aggarwal, D.K. Das, and R.K. Gupta. 2003. Trends of climatic potential and on-farm yields of rice and wheat in the Indo-Gangetic Plains. Field Crops Res. 80:223–234.
• Pathak, H., R. Singh, A. Bhatia, and N. Jain. 2006. Recycling of rice straw to improve crop yield and soil fertility and reduce atmospheric pollution. Paddy Water Environ. 4:111–117.[CrossRef]
• Prihar, S.S., and B.S. Sandhu. 1987. Irrigation of field crops, Principles and practices. Indian Council of Agricultural Research. New Delhi, India.
• Richards, S.J. 1965. Soil suction measurements with tensiometers. p. 153–163. In C.A. Black (ed.) Methods of soil analysis. Agron. Monogr. 9. ASA, CSSA, and SSSA, Madison, WI.
• Sayre, K.D., and O.H. Moreno Ramos. 1997. Applications of raised-bed planting systems to wheat. Wheat Spec. Rep. No. 31. CIMMYT, Mexico.
• Seckler, D., U. Amarasinghe, D. Molden, R. De Silva, and R. Barker. 1998. World water demand and supply, 1990 to 2025: Scenarios and issues. Res. Rep. 19. Int. Water Management Inst., Colombo, Sri Lanka.
• Sharma, P.K., L. Bhushan, J.K. Ladha, R.K. Naresh, R.K. Gupta, V. Balasubramanian, and B.A.M. Bouman. 2002. Crop–water relations in rice–wheat cropping systems and water management practices in a marginally sodic, medium-textured soil. p. 223–235. In B.A.M. Bouman et al. (ed.) Water-wise rice production. IRRI, Los Baños, the Philippines.
• Sharma, H.C., S.D. Dhiman, and V.P. Singh. 1994. Rice–wheat cropping system in Haryana: Potential, possibilities and limitations. p. 27–39. In S.D. Dhiman et al. (ed.) Proc. of the Symp. on Sustainability of Rice–Wheat System in India. CCS Haryana Agric. Univ., Regional Research Station, Karnal, India.
• Sharma, P.K., J.K. Ladha, and L. Bhushan. 2003. Soil physical effects of puddling in rice–wheat cropping system. p. 97–114. In J.K. Ladha et al. (ed.) Improving the productivity and sustainability of rice–wheat systems: Issues and impacts. ASA Spec. Publ. 65. ASA, CSSA, and SSSA, Madison, WI.
• Shukla, A.K., J.K. Ladha, V.K. Singh, B.S. Dwivedi, R.K. Gupta, S.K. Sharma, V. Balasubramanian, Y. Singh, H. Pathak, A.T. Padre, and R.L. Yadav. 2004. Calibrating the leaf color chart for N management in different genotypes of rice and wheat in a system perspective. Agron. J. 96:1606–1621.[Abstract/Free Full Text]
• Singh, Y., and J.K. Ladha. 2004. Principles and practices of no-tillage systems in rice–wheat systems of Indo-Gangetic plains. p. 167–207. In R. Lal et al. (ed.) Sustainable agriculture and the rice–wheat systems. Marcel Dekker, New York.
• Sondhi, S.K., M.P. Kaushal, and P. Singh. 1994. Irrigation management strategies for rice–wheat cropping system. p. 95–104. In S.D. Dhiman et al. (ed.) Proc. of the Symp. on Sustainability of Rice–Wheat Systems in India. CCS Haryana Agricultural Univ., Regional Research Station, Karnal, India.
• Tabbal, D.F., B.A.M. Bouman, S.I. Bhuiyan, E.B. Sibayan, and M.A. Sattar. 2002. On-farm strategies for reducing water input in irrigated rice; case studies in the Philippines. Agric. Water Manage. 56:93–112.
• Toung, T.P., and S.I. Bhuiyan. 1994. Innovations towards improving water-use efficiency in rice. Paper presented at the World Bank's 1994 Water Resource Seminar, 13–15 Dec. 1994. Landsdowne, VA, USA.
• Vories, E.D., P.A. Counce, and T.C. Keisling. 2002. Comparison of flooded and furrow irrigated rice on clay. Irrig. Sci. 21:139–144.
• Yoder, R.E. 1936. A direct method of aggregate analysis and study of the physical nature of erosion losses. J. Am. Soc. Agron. 28:337–351.
• Zadoks, J.C., T.T. Chang, and C.F. Konzak. 1974. A decimal code for the growth stages of cereals. Weed Res. 14:415–421.[CrossRef]

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