The Rice-Wheat Cropping System of South Asia

Efficient Production Management

Palit Kataki, Suresh Chandra Babu

• Publisher: CRC Press
• Year: 2021
• ISBN:
  9781000447903
• Edition: 1
• Topic: Business
• Subtopic: Industria agricola
• Index: Business

The lives of more than a billion people depend on the answer!

This valuable book surveys the problems of the rice-wheat cropping system practiced on the Indo-Gangetic Plain (IGP). Introduced at the time of the Green Revolution, it transformed agriculture and produced thirty years of bumper crops. The Rice-Wheat Cropping System of South Asia: Efficient Production Management offers scientific analysis of the aftereffects of this intense cropping.

The Rice-Wheat Cropping System of South Asia: Efficient Production Management focuses on the questions of soil depletion, pest infestation, and soil alkalinity as elements of declining productivity. Along with clear charts, maps, and graphs, it provides practical suggestions for improving and maintaining the productivity of this irreplaceable farmland.

The Rice-Wheat Cropping System of South Asia looks at the problems that have arisen for both the rice and wheat phases, including:

• depletion of micronutrients
• degradation of major nutrients from unbalanced fertilization practices
• infestations of nematodes
• increasing soil alkalinity as a result of irrigation

It also suggests solutions for maintaining productivity, including:

• integrated pest management
• sustainable agriculture
• micronutrient fertilizers

This informative book and its companion volume, The Rice-Wheat Cropping System of South Asia: Trends, Constraints, Productivity and Policy, are essential planning tools for agronomists, policymakers, and agroeconomists. It is also a useful reference for anyone interested in the problems of famine and intensive cropping not only in South Asia but in the world.

Efficient Management of Primary Nutrients in the Rice-Wheat System

Yadvinder-Singh

Bijay-Singh

Yadvinder-Singh and Bijay-Singh are Senior Soil Chemists, Department of Soil Science, Punjab Agricultural University, Ludhiana, Punjab-141004, India.

[Haworth co-indexing entry note]: “Efficient Management of Primary Nutrients in the Rice-Wheat System.” Singh-Yadvinder, and Bijay-Singh. Co-published simultaneously in Journal of Crop Production (Food Products Press, an imprint of The Haworth Press, Inc.) Vol. 4, No. 1 (#7), 2001, pp. 23–85; and: The Rice-Wheat Cropping System of South Asia: Efficient Production Management (ed: Palit K. Kataki) Food Products Press, an imprint of The Haworth Press, Inc., 2001, pp. 23–85. Single or multiple copies of this article are available for a fee from The Haworth Document Delivery Service [1–800–342–9678, 9:00 a.m. -5:00 p.m. (EST). E-mail address: [email protected]].

SUMMARY. A better understanding of the nutrient economy in relation to productivity is immensely important to develop a sustainable rice-wheat cropping system in the Indo-Gangetic Plain (IGP). Fertilizer (N, P and K) use pattern for the rice-wheat system in the IGP varies greatly at the country, state, village, and farmer field level. In general, fertilizer use is conspicuously more in the western compared to the eastern IGP. Continuous government subsidies on nitrogenous fertilizers have helped create imbalanced N, P, and K fertilizer use by farmers. Removal of P and K by the rice-wheat system far exceeds its additions through fertilizers and recycling.

Nitrogen from rice-wheat systems can often be lost via ammonia volatilization, denitrification and leaching. Nitrification acts as a key process in determining fertilizer-use-efficiency by crops as well as N losses from soils. Loss of N via ammonia volatilization can be substantial when urea is top-dressed. Placement of fertilizer N beneath the soil surface or transportation of N to subsoil layers along with irrigation water can be a useful management option to reduce NH₃ volatilization losses. Water management in rice fields influences the extent of N losses due to nitrification-denitrification. Up to 50% of the applied N can be lost through denitrification when alternating aerobic-anaerobic conditions prevail in rice fields. Leaching losses of N as NO₃ are minimal under wheat but can be substantial under rice grown in readily percolating coarse textured soils found in northwestern India. Irrespective of its source, application of fertilizer N at 120 kg N ha⁻¹ has been the recommended level for rice and wheat in most of the Indo-Gangetic Plain. However, recent trend indicates the use of more than 150 kg N ha⁻¹, particularly to rice grown in northwestern Indian states, where more than 10 t ha⁻¹ grain yield per annum is being harvested from the rice-wheat system. Efforts to increase the notoriously low fertilizer N use efficiency in rice through modifications in N sources have been promising for slow release N fertilizers. In spite of the distinct advantage of using supergranules of urea in fine textured soils, its use is not popular amongst farmers due to the lack of a suitable mechanical applicator. Application of fertilizer N in three and two equal split doses to rice and wheat, respectively, has proved to be an efficient management option. Need based fertilizer N applications to rice using chlorophyll meter is promising for increasing the fertilizer use efficiency. In northwestern India, nitrate content in ground water bodies is continuously increasing and it has been linked to the inefficient fertilizer N use in the rice-wheat system.

In the rice-wheat system, response of wheat to fertilizer P application is more common than its application to rice. Moreover, the residual response of P applied to wheat on rice is greater than that applied to rice on wheat. The availability of soil and fertilizer P increases under submergence and at high temperatures prevailing during the rice season. Thus rice could meet its P requirement from the soil and the residual fertilizer P, when the recommended P fertilizer has been applied to the preceding wheat crop. Improved chemical tests for predicting indigenous soil P supply need to be developed to predict response of rice and wheat to fertilizer P in the cropping system. In neutral and alkaline soils, fertilizers containing P in water-soluble forms are more effective than those containing P soluble in citric acid. Nitrophosphates containing 60% or more of total P in water-soluble forms have been found to be as efficient as diammonium phosphate and superphophates in wheat. In some neutral and acidic soils, a part of the total fertilizer P supplied through diammonium phosphate and superphosphates can be replaced by rock phosphate.

Most of the soils in the Indo-Gangetic Plain contain illite as dominant clay mineral and are medium to high in ammonium acetate (1 M, pH 7.0) extractable K. Therefore, response of rice and wheat to applied K are generally small. Farmers apply very small quantities of K fertilizers to rice and wheat. Total annual K removal by the rice-wheat system is quite large causing depletion of soil K supply. The suitability of ammonium acetate extractable K as an index of plants available K for different soils varying in texture and clay mineralogy remains controversial. Dynamic soil test using resin capsule, which integrates intensity, quantity and delivery rate measures of P and K to rice and wheat can overcome many of the theoretical limitations associated with rapid chemical extraction. [Article copies available for a fee from The Ha worth Document Delivery Service: 1-800-342-9678. E-mail address: <[email protected]> Website: <http://www.HaworthPress.com> © 2001 by The Haworth Press, Inc. All rights reserved.]

KEYWORDS. Fertilizers, nitrogen, phosphorous, potassium, rice, wheat

INTRODUCTION

Rice followed by wheat is a dominant cropping sequence under a range of management regimes in the Indo-Gangetic Plains of South Asia. It covers more area in semi-arid ecoregions than in humid or subhumid regions and is practiced essentially under irrigated conditions. Productivity of this intensive agricultural production system spread over 12 million ha in India, Pakistan, Nepal and Bangladesh (Huke and Huke, 1992) varies greatly due to variations in soil, climate, and nutrient...