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ABSTRACT

Rice-Wheat system is one of the most common cropping systems of Indian agriculture but, if we consider the sustainability of rice-wheat cropping system, it can be predicted that India’s food basket states or major rice-wheat cropping system belt (Punjab, Haryana and Western UP) may become critically food insecure in upcoming 20-30 years. In this article we have discussed the prevalent rice-wheat cropping systems areas, problems of this system and possible solutions/alternatives to enhance sustainability of rice-wheat cropping system.

 

Keywords: Rice-wheat, Cropping system, Sustainability, Climate change, Challenges

 

Rice-Wheat system is one of the most common cropping systems of the country; however, other cropping systems such as Jowar-Wheat, Bajra-Wheat, Maize-Wheat, Pulse-Wheat, Cotton-Wheat, Soybean-Wheat etc. are also followed under irrigated regions. Declining water tables, erratic rainfalls, continuous climate change, decreasing soil fertility. Herbicide resistance in weeds (P. minor, R. deantus) and residue burning in field are major issue associated with rice-wheat system are the major factors that need to be considered while concerning about the sustainability of rice-wheat system. Furthermore, rice is water-intensive crop and thereby, it is depleting the ground water ultimately leading to the lesser water availability for irrigation purposes. Moreover, imbalanced use of nutrients, herbicides and other fertilizers in a non-judicious manner making this system less sustainable. Table 1 shows prevalent cropping system involving wheat and total area under wheat cultivation in major wheat growing states of India.

Table 1: Major cropping system involving wheat in wheat growing states of India

State	Major Wheat-based cropping System	Total area under wheat (lakh ha)
Bihar	Rice-Wheat, Maize-Wheat, Sesame-Wheat	21.57
Chhattisgarh	Soybean-Wheat, Rice-Wheat, Sorghum-Wheat, Cotton-Wheat	1.00
Gujarat	Groundnut-Wheat, Rice-Wheat, Maize-Wheat, Cotton-Wheat, Pigeon Pea-Wheat	7.97
Haryana	Rice-Wheat, Sorghum-Wheat, Cotton-Wheat, Bajra-Wheat, Maize-Wheat	25.53
Himachal Pradesh	Maize-Wheat	3.19
Jammu & Kashmir	Rice-Wheat, Maize-Wheat	2.88
Jharkhand	Rice-Wheat	1.64
Karnataka	Groundnut-Wheat	1.58
Madhya Pradesh	Rice-Wheat, Sorghum-Wheat, Soybean-Wheat, Cotton-Wheat	77.22
Maharashtra	Soybean-Wheat, Bajra-Wheat, Rice-Wheat, Cotton-Wheat	8.34
Punjab	Rice-Wheat, Cotton-Wheat, Maize-Wheat	35.20
Rajasthan	Sorghum-Wheat, Maize-Wheat, Bajra-Wheat	29.98
Uttar Pradesh	Rice-Wheat, Bajra-Wheat, Sorghum-Wheat, Sugarcane-Wheat	98.56
West Bengal	Rice-Wheat	1.12

* https://aps.dac.gov.in/APY/Public_Report1.aspx

Major problems of Rice-Wheat cropping system

In Indian agriculture, sustainability and stability of rice-wheat cropping system are emerging as a serious issue of great debate. Following are the major problems that need to be addressed:

(a) Declining water tables

Due to the overexploitation of the available ground water resources, mainly in Northwest part of our country, water table is declining day by day therefore, ground water resources are depleting in a drastic manner. Furthermore, ground water possesses highest efficiency in terms of irrigation and developing surface water-based irrigation strategies is a very expensive and deteriorating process.

(b) Reducing Soil Fertility

Nutrient mining and non-judicious and imbalanced application of fertilizers are deteriorating the soil fertility in a drastic manner. Furthermore, out of 17 essential nutrients for plants, C, H and O are being provided by air and rest 14 are being absorbed from soil. At present, farmers are using N, P, Zn etc to enhance productivity in their fields; however, status of other important micronutrients required for overall growth and development of the plant is declining and due to the continuous non replenishment, these nutrients might not be available in sufficient amount to meet the crop requirements in near future. The well-fertilized crops of rice and wheat meet ~50.8% of their nitrogen requirements from the soil, which may results in poor factor productivity of RWCS. The situation of nutrient mining is more alarming in the highly productive areas of the Indo Gangetic Plains (IGP) of India, where widely cultivated RWCS is supported with inadequate and unbalanced nutrient management practices, multi-nutrient deficiencies. Some long-term experiments in India advocated the application of 120 kg N ha−1 to each crop in RWCS for fetching higher economic yield where, the net negative balance is 2.22 M t annum−1 for NPK in IGP (Tondon, 2007).

(c) Weeds infestation problems and management

For most of the crops, critical stage of crop competition lasts 30-35 days after sowing. Lack of integrated weed management practices led to the emergence of some problematic weeds such as Phalaris minor which has developed resistance to a very important and effective herbicide - isoproturon. The use of other herbicides, namely, Imazethapyr and Pyroxasulfones have been a very effective method of containing weeds for growth. Integrated Weed Management includes a number of effective weed control measures such as optimum plant density, optimum sowing time, optimum nutrient and irrigation water management combined with chemical methods, which leads to effective weed control thus, preventing any weed replacement plants.

(d) Diminishing factor productivity

Although yields are still stagnant and declining or may not be able to reach the desired levels under certain conditions, the input use pattern indicates a continuous increase in nutrient demand, increased use of pesticides and irrigation water. This means that the efficiency of inputs decreases which increases the production costs. The high production cost of any crop increases the risk. The total revenue from the Rice-Wheat Cropping System is declining and farmers are finding it difficult to maintain their economic benefits per unit. Reducing the cost of production in various ways, i.e., operating costs including land preparation, planting machine, cultural operations and harvesting/threshing and conservation technologies may increase farmers` income.

(e) Insect-pests and other pathogens

The lush rice and wheat crops with the liberal use of nitrogenous fertilizers and due to constant favourable environment have become a paradise to create a complex of pests and diseases. Rust (Stripe rust) has been a major concern and only occurs during peak stages of crop growth. Propiconazole has been found effective in controlling this threat. Spraying of Propiconazole and Tebuconazole in other season is also recommended to avoid any accumulation of resistance. Karnal Bunt is another problem that limits its productivity. Disease-resistant varieties have been developed but the wheat fields where the disease has occurred have been suggested to be kept for other than wheat cultivation for at least three years and at the same time soil and seed treatment should be done even in the surrounding areas.

Strategies to enhance stability and sustainability of the rice-wheat cropping system

Continuous use of rice-wheat cropping system is depleting natural resources thus, challenging the sustainability of this system in near future. Therefore, important preventive measures are needed to be addressed to sustain and stabilize the rice-wheat cropping system (Ladha et al., 2002). Following are the few strategies that may contribute in enhancing sustainability of rice-wheat cropping system:

(a) Zero or reduced tillage

Zero tillage has been proven to be a breakthrough in wheat cultivation. The long duration rice cultivation before wheat usually overlaps the following wheat season thereby induces delayed sowing of wheat. Zero tillage reduces the time taken for land preparation besides economizing the cost of production resulting in increasing the margin of profit for the wheat growers. Additionally, weed infestation is also reduced in zero tillage areas.

 (b) Use of green manure

After harvesting of wheat and transplanting of rice, there is gap of nearly 40-45 days which can be used for raising the good green manure crops. Any leguminous crop such as Sesbania is a suitable choice as it grows very finely on marginal soils and can accumulate about 250q ha ^-1 biomass in just seven weeks. Therefore, it contributes nearly 60-80 kg N ha in the soil. Thus, green manure can compensate much of the nitrogen requirement of subsequent crop that is rice (Acharya et al., 2003).

(c) Proper management of crop residue

Due to very short time availability between both the crops, residue management is a serious issue. Paddy straw management is becoming a matter of serious concern as burning of paddy straw in some rice growing areas is deteriorating the environmental conditions and declining the air quality index. Furthermore, wheat residue management is more difficult if a third crop is grown in summer. Since, maintaining sustainability of rice-wheat cropping system is important in terms of profitability and production therefore, proper management and retention of some of the crop residue is important. In-situ management practices like residue retention or incorporation in the field and use of residue in making of thatching material and biochar, can be some viable alternatives.

(d) Efficient use of water resources

Water use efficiency in rice-wheat cropping system (RWCS) is generally low. Water management in RWCS can be optimized by appropriate soil management by reducing percolation, proper scheduling of irrigation, use of ground water and utilization of rain water. Therefore, proper and judicious use of available water resources may contribute in enhancing productivity (Ladha et al., 2003).

(e) Adoption of direct seeded rice (DSR)

Cultivation of rice by DSR in rice-wheat cropping system may save 30% water as compared to the conventional methods of rice cultivation such as transplanting. Furthermore, this pattern enhances the water use efficiency without compromising with yield and also reduces the emission of methane gas that causes severe adverse impact in environment.

References:

Regmi, A.P., Ladha, J.K., Pathak, H., Pasuquin, E., Bueno, C., Dawe, D., Hobbs, P.R., Joshy, D., Maskey, S.L. & Pandey, S.P. (2002). Analyses of yield and soil fertility trends in a 20-year rice–rice–wheat experiment in Nepal. Soil Science Society of America Journal, 66, 857–867.

Acharya, C.L., Subba Rao, A., Biswas, A.K., Reddy, K.S., Yadav, R.L., Dwivedi, B.S., Shukla, A.K., Singh, V.K. & Sharma, A.K. (2003). Methodologies and Package of Practices on Improved Fertilizer Use Efficiency Under Various Agroclimatic Regions for Different Crops/Cropping Systems and Soil Conditions. Indian Institute of Soil Science (ICAR), Bhopal (Madhya Pradesh), India.

Ladha, J.K., Fischer, K.S., Hossain, M., Hobbs, P.R. & Hardy, B. (2000). Improving the productivity and sustainability of rice-wheat systems of the Indo-Gangetic Plains: A synthesis of NARS-IRRI partnership research. Discussion Paper 40. IRRI, Los Banos, Philippines.

Ladha, J.K., Dawe, D., Pathak, H., Padre, R.L., Yadav, R.L., Singh, B., Singh, Y., Singh, P., Kundu, A.L., Kundu, R., Sakal, R., Ram, N., Regmi, A.P., Gami, S.K., Bhandari, A.L., Amin, R., Yadav, C.R., Bhattaria, E.M., Das, S., Aggarwal, H.P., Gupta, R.K. & Hobbs, P.R. (2003). How extensive are yield declines in long-term rice-wheat experiments in Asia? Field Crops Research, 81, 159–180.

 

Tandon, H. L. S. (2007). Soil nutrient balance sheets in India: Importance, status, issues, and concerns. Better Crops–India, 1, 15-19.

 

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