Evaluation of alternative tillage and crop establishment methods in a rice–wheat rotation in North Western IGP
Introduction
Rice–wheat (RW) rotation is of immense importance for the food security and livelihoods in South Asia (Ladha et al., 2003 for review). The system occupies about 18 million ha in Asia, of which 13.5 million is in the Indo-Gangetic Plains (IGP) of Bangladesh, India, Nepal, and Pakistan, and feeds about a billion people (20% of the world population). The widespread adoption of high-yielding cereals along with improved crop management practices and availability of irrigation water and chemical inputs during the Green Revolution (GR) has led to impressive increase in system productivity. But evidence is now appearing that the productivity is plateauing and total factor productivity is declining because of a fatigued natural resource base and therefore, sustainability of this cropping system is at risk (Ladha et al., 2003). In addition, environmental degradation, increasing water scarcity, labor shortage and socioeconomic changes are seen as the other major contributors to the stagnation of rice–wheat productivity in the IGP (Erenstein et al., 2007, Rijsberman, 2006).
The two major cereals in the RW rotation has contrasting edaphic requirement. For rice, soil is puddled (wet tillage) and kept under continuous submergence. In contrast, wheat is grown in upland well-drained soil having good tilth. Puddling and transplanting are highly labor, water, time and energy intensive. The advantages of puddling include weed suppression, reduction in percolation losses, and creation of anaerobic conditions, all of which are beneficial for rice. However, repeated and continuous puddling destroys soil structure, creates hard pans at shallow soil depth, and delays planting which in turn adversely affect the performance of succeeding wheat (Hobbs and Moris, 1996). It has been reported that on average wheat yield is reduced by 8% when sown after puddled transplanted rice compared to wheat sown after direct-seeded rice in unpuddled conditions (Kumar et al., 2008). Puddling can also delay wheat planting which results in yield loss of 35–60 kg day−1 ha−1 in the IGP (Pathak et al., 2003).
Water and labor scarcity is becoming major concern for the productivity and sustainability of the rice–wheat cropping system in South Asia. Agriculture's share of freshwater supplies is likely to decline by 8–10% because of increasing competition from the urban and industrial sectors (Toung and Bhuiyan, 1994, Seckler et al., 1998). In many parts of Asia, overexploitation and poor management of groundwater has led to dropping water table and negative environmental impacts. Conventional flooded rice receiving the largest amount of fresh water compared to any other crop is the major contributor to the problems of declining groundwater table (0.1–1.0 m year−1) and increasing energy use (Singh et al., 2002). The problem has further been intensified with the timely unavailability of labor, and increasing labor wages.
Conventional tillage/crop establishment in an agro-system is the most input intensive process and therefore more efficient alternatives are urgently needed. As part of our comprehensive program at rice–wheat consortium (RWC), we have been addressing these burning issues through designing and testing various alternative options (Ladha et al., 2009a). Potential solutions include a shift from intensive tillage to no or reduced tillage and/or from transplanting to direct-seeding. There can be several other modifications such as transplanting in unpuddled soil especially in light textured soil. The practice of transplanting on unpuddled soil is a potential technology for those farmers who are skeptical about direct-seeded rice to avoid adverse effect of puddling on succeeding wheat crop. Puddling (wet tillage) takes upto 30% of total irrigation water application in rice in light textured soils (Aslam et al., 2002), so the land preparation is more water-efficient for unpuddled transplanted or dry direct-seeded rice as compared to puddled transplanted rice. Saharawat et al. (2009) and Reddy et al. (2004) have reported similar yield and water application in unpuddled and puddled transplanted rice in farmer participatory trails in Haryana, India. Previously, we reported that dry direct-seeding of rice and wheat after no-tillage performed as well as the conventional practice but with significant savings in water and labor use (Bhushan et al., 2007). In dry direct-seeded rice, with alternate wetting and drying cycles, the crop is subjected to greater weed competition than transplanted rice because weeds emerge before or at the same time as the rice. Therefore, heavy weed infestation is a major problem in direct-seeded rice and its success lies is effective weed control measures (Rao et al., 2007).
The alternative tillage and crop establishment are site specific and therefore evaluations under wider agro-ecological conditions is important to have significant adoption (Ladha et al., 2009a). Following these leads, a 2-year study was conducted in Haryana, a major food basket of India to evaluate the performance of various modifications of tillage and rice establishment practices with a goal of finding most suitable ones with a potential to cover large area of 1.23 million ha in the state and eventually in a much larger area with a similar ago-ecological condition in the IGP. Specifically, we monitored following key performance indicators to evaluate various practices: crop productivity, irrigation water application, water use efficiency, energy use and net returns.
Section snippets
Site and soil
Field studies were conducted at research farm (29°51′N, 76°41′E, and 241 m above mean sea level) of College of Agriculture, Chaudhary Charan Singh Haryana Agricultural University, Kaul (Kaithal), Haryana, India, in 2005–2006 (year 1) and 2006–2007 (year 2). Haryana is an intensively rice–wheat growing state in India. Conventional rice–wheat rotation was being followed on the field from last 15 years. The climate of the area is semi-arid, with an average annual rainfall of 750 mm (75–80% of which
Rice and wheat grain yield and system productivity
In both the years, tillage and crop establishment methods had a significant effect on rice grain yield. In year 1 (2005), yields of conventionally transplanted (T1), unpuddled transplanted (T2), and no-till transplanted (T3) plots were similar but higher than wet and dry direct-seeded rice (T4 and T5) plots (Table 2). Yields of wet and dry direct-seeded rice were 6–8% lower than transplanted rice (T1, T2, and T3). In year 2 (2006), grain yields of wet and dry direct-seeded rice (T4 and T5) were
Discussion
In the rice–wheat system of the IGP, rice is grown traditionally by transplanting seedlings into puddled soil (wet tillage) which requires large amount of water and labor, and often delays planting of succeeding wheat crop (Sharma et al., 2002). In the recent years, increasing efforts are devoted to find more efficient alternatives of current intensive tillage and crop establishment practices (Ladha et al., 2009b for review). Numerous on-station and on-farm results show that direct-seeding on
Conclusion
This 2-year study builds on our earlier studies (Bhushan et al., 2007, Ladha et al., 2009a, Saharawat et al., 2009) which aimed at evaluating various new practices of tillage and crop establishment in the rice–wheat rotation which are superior to conventional puddling and transplanting practice. It is clear that alternative tillage and crop establishment practices may not perform similarly in all agro-ecological conditions and savings especially in terms of irrigation water would depend on
References (37)
- et al.
Puddling and N management effects on crop response in a rice–wheat cropping system
Soil Till. Res.
(1995) - et al.
Relationship between ripening phase productivity and crop duration, canopy photo-synthesis, and senescence in transplanted and direct-seeded lowland rice
Field Crops Res.
(1991) - et al.
Role of herbicide-resistant rice in promoting resource conservation technologies in rice–wheat cropping systems of India: a review
Crop Prot.
(2008) - et al.
Trends of climatic potential and on-farm yields of rice and wheat in the Indo-Gangetic Plains
Field Crops Res.
(2003) - et al.
Weed management in direct-seeded rice
Adv. Agron.
(2007) Water scarcity: fact or fiction?
Agric. Water Manage.
(2006)- et al.
Evaluation of mulching, intercropping with Sesbania and herbicide use for weed management in dry-seeded rice (Oryza sativa L.)
Crop Prot.
(2007) - et al.
On-farm strategies for reducing water input in irrigated rice; case studies in the Philippines
Agric. Water Manage.
(2002) - et al.
Efficiency and energy use in puddling of lowland rice grown on vertisols in Central India
Soil Till. Res.
(2006) - et al.
Water saving strategies for irrigated rice
J. Drain. Water Manage.
(2002)