ABSTRACT
College of Resources and Environmental Sciences, China Agricultural University, Beijing, China
CONTENTS
39.1 Explaining the Benefits of Intercropping.................................................................... 560
39.1.1 The Competitive-Recovery Production Principle......................................... 561
39.1.1.1 Dominant-Species Yield Advantage in Interspecific
Competition........................................................................................ 562
39.1.1.2 Subordinate-Species Compensation during a Later
Growth Stage...................................................................................... 562
39.1.2 Interspecific Belowground Growth Facilitation by Nutrient
Mobilization........................................................................................................ 563
39.1.2.1 Improvement in the Fe Nutrition of Groundnut through
Maize Intercropping.......................................................................... 563
39.1.2.2 Benefits to Maize from Association with Fava Bean................... 564
39.1.2.3 Chickpea Facilitation of Phosphorus Nutrition in
Associated Wheat .............................................................................. 564
39.1.2.4 Intercropping to Reduce Nitrate Accumulation in the
Soil Profile........................................................................................... 564
39.1.3 Interspecific Competition and Facilitation: Concurrent Effects ................. 565
39.2 The Rice-Wheat Rotation Cropping System ............................................................. 566
39.2.1 Manganese Deficiency in Wheat Induced by Rice-Wheat Rotation ........ 566
39.2.1.1 Manganese Accumulation in the Soil Profile and Effect on
Wheat Growth.................................................................................... 566
39.2.1.2 Different Responses of Wheat and Rapeseed to
Manganese Stress............................................................................... 567
39.2.1.3 Improvement of Wheat Manganese Nutrition in
Rice-Wheat Rotation through Rhizosphere Management......... 568
39.2.2 Application of Nonflooded Mulching Cultivation for
Rice-Wheat Rotation ........................................................................................ 569
39.2.2.1 Aggregate System Productivity ...................................................... 569
39.2.2.2 Mulch-Nutrient Interactions .......................................................... 569
39.2.2.3 Nutrient Balance ................................................................................ 570
39.2.3 Soil Properties..................................................................................................... 571
39.3 Discussion ........................................................................................................................ 572
Acknowledgments ..................................................................................................................... 572
References ................................................................................................................................... 572
Most of the current crop production in China produces high outputs in terms of grain
and fiber yields per unit area, but with a corresponding requirement for high inputs,
including seeds, irrigation, and various chemicals. At the same time, China is known
for the low quality of its outputs, and there is increasing concern for environmental
problems. China, with only 7% of the world’s arable land area, must support 22% of the
world’s population. At present, the arable land area in China is decreasing due to the
expansion of land uses for nonagricultural purpose, while the population in China
continues to increase. For some time to come, China must expect an annual population
increase of 10 million while there is an annual decrease of 350,000 ha of cultivated land.
To support a larger population with a declining farmland area, China needs to develop
production systems that make the most efficient use of the limited land resources,
improve soil fertility and productivity, and increase farming profitability.