The economic benefit of planting spring-corn in rice field and its efficient technique for system coupling

According to the results of long-located experiments from 1990 to 2000，the comparison between wheat-corn-rice pattern of planting spring-corn in rice field and the conventional wheat-rice pattern was studied．The yield of the wheat-corn-rice pattern is 14254kg／hm²，increasing by 17．69％；the organic energy，the inorganic energy，and the total energy increase by 3．54％，8．37％ and 7．90％ ，respectively，the energy output ofgrain and biomass increase by 16．99％ and 15．12％ ，and it has the higher energy output：input value；the surplus rates of N ，P₂O5，and K₂O increase，in the soil organic matter balance many surpluses exists，and the surplus rate is 81．18％;the increa sed net profit ratio is 22．42％ and the marginal benefit-cost ratio is 3．33．Efficient techniques for system coupling of planting spring-corn in rice field include that the winter and spring can be freed，and the wheat can be changed to the economic crops；spring-corn adopts the cuhivation techniques of plastic film covered at two stages，the agronomic measures for spring corn with yield more than 8250kg／hm² are 7920～8990 plant／hm² in planting density．with the 288．6～352．4kg／hm² N fertilizer application and by the treatment of 304．6～498．0 mg／kg Eth at the 11～12 leaf age of the plants；late double-cropped rice adopts the cultivationtechniques of dry-raising seedlings in plastic tray and cast-transplanting，the agronomic measures for the rice with yield more than 7500 kg／hm² are planting strong and long seedlings aging more than 35d(2．25～2．4 million plant／hm² of basic seeding with the 225～255kg／hm² N fertilizer application)．