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Analyses on the Emergies of Multiple Compound Cropping Systems from Double-Cropping Paddy Fields in Jiangxi Province
- SUN Wei-Min-1, HUANG Guo-Qin-1, CHENG Jian-Feng-2, LIU Bin-Bin-1
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Scientia Agricultura Sinica. 2014, 47(3):
514-527.
doi:10.3864/j.issn.0578-1752.2014.03.011
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【Objective】 Grain problem is always a hot issue concerned by the world. Seeking efficient cropping patterns, improving land utilization efficiency and enhancing grain production are the most urgent researches at present. From the results of related researches fields at home and abroad, multiple cropping patterns are the important approaches of utilizing natural resources and increasing crop production, so agriculture all over the world is developing toward the direction of multiple cropping patterns. In 1987, H T Odum, the famous ecologist in American, proposed the theory of emery analysis to explore the function principles and simulation technology of the complicated terrestrial ecosystems, and extended it to the ecological, environmental, social and economic systems involved in human. Since 1980’s, applying energy inputs and outputs to measure the good or bad of different ripe cycles and cropping patterns were focused and applied widely, which were beneficial for regulating the relationship between ecological environments and economic developments and had important practical values of scientific estimation and reasonable utilizations of natural resources. In the experiment, the resource utilizations, input and output benefits of multiple compound cropping systems from double-cropping paddy fields were clarified, which provided a theoretical foundation for the farming system reforms of winter compound cropping patterns in double-cropping paddy fields of south China and sustainable development of farmland ecosystems, the scientific and technological supports of moving forward roundly regional modern agriculture development and agricultural modernization constructions, reference frames of increasing grain production, farmers income and rural prosperity in the nation and regions. 【Method】 Energies of crop economic yields, photosynthetic productivities, solar energy utilization efficiencies, inputs, outputs, operating efficiencies and environmental loads of seven multiple cropping systems in Yujiang country of Jiangxi province were analyzed comprehensively with the theories and methods of emery analyses on the basis of data from field location experiments and related statistic yearbooks. 【Result】 The results showed that the energies of crops economic yields in winter multiple cropping were 217.57×106-229.7×106 kJ•hm-2 and higher than 213.5×106 kJ•hm-2 in winter fallow (T1); and energies of crops economic yields in the T4, T6 and T7 were significantly higher than those in the other treatments, the increasing percent of energy in T6 was 8.5% and the highest. Energy increasing percent of T6 was the highest in 2008-2010, which indicated that T6 had a better superiority and stability. Photosynthetic productivities (11.99-14.03 g•m-2•d-1) and solar energy utilization efficiencies (1.46%-1.70%) in winter multiple cropping were markedly significantly higher than those (10.55 g•m-2•d-1 and 1.28%, respectively) in T1, the average increasing ranges were 14.4%-34.8% with the highest increasing percent (34.8%) of T3, and the changes of photosynthetic productivities and solar energy utilization efficiencies were exactly alike. Energies of crops economic yields in winter multiple cropping rotations were 220.9×106-229.7×106 kJ•hm-2 and higher than 217.5×106 kJ•hm-2 in winter multiple continuous cropping (T2), and the increasing percent of energy in T6 was 6.1% and was the highest, but no significant difference was found among all treatments. Winter multiple cropping rotations reduced crop photosynthetic productivity to a certain extent, photosynthetic productivities (11.99-13.10 g•m-2•d-1) in winter multiple crop rotations were lower than 13.67 g•m-2•d-1 in T2 except the higher in T3, the average decreasing ranges were 4.2%-12.4% with the highest reduction of T4. The solar energy utilization efficiencies in T3 (1.70%) and T6 (1.67%) were significantly higher than those in the other treatments (1.46%-1.58%) which decreased with the highest reduction of T4 and T5 in comparison with T1. Emergy analyses indicated that the emergy inputs and outputs of all treatments existed obvious differences; the least of net loss of topsoil was 2.98×1016 sej in T1, the most was 3.83×1016 sej in T5; the least of industrial supplement emergy was 1.62×1017 sej in T1, the most was 2.98×1017 sej in T4 and nearly two times in T1; the least of organic emergy was 6.55×1015 sej in T1, the most was 1.19×1016 sej in T7 and nearly two times in T1; the least of output emergy was 1.39×1016 sej in T1, the most was 5.42×1016 sej in T6 and nearly four times in T1. Emergy input ratios (3.12-4.57) in winter multiple cropping were higher than 2.84 in T1 except the lower of 2.81 in T3, the increasing percents in T4 and T5 were 61.1% and 50.4%, respectively; but only emergy input ratio (0.13) in T4 was higher than 0.08 in T1, those (0.06-0.07) in the other treatments were lower. Emergy ratios of environmental resources to total inputs in the most treatments were 0.17-0.26 with the maximum reduction of T4 and lower than that in winter fallow, which showed that winter compound cropping patterns were favorable to protecting farmland environmental resources. Emergy ratio of unrenewalbe to total environmental resources in all winter compound cropping patterns were 0.10-0.15 and higher than that in T1, which suggested that planting winter crops mostly depended on the unrenewalbe environmental resources and could increase soil loss. Emergy ratio of industrial supplement to total inputs in all treatments exceeded 0.8, but had no obvious differences, which indicated that the productions of all cropping patterns depended on the industrial inputs and counted against agricultural sustainable development. 【Conclusion】In conclusion, planting winter crops in double-cropping paddy fields were better for increasing photosynthetic productivities and solar energy utilization efficiencies of paddy fields. Photosynthetic productivities and solar energy utilization efficiencies of planting economic crops except mixed green manure in winter multiple cropping rotations were lower than those in winter multiple continuous cropping. Planting broad bean and pea in double-cropping paddy fields in winter were more superior to fallow-double cropping rice system; but planting rape in double cropping rice system in winter was one of the high input and output patterns for sustainable developments; thus, planting rape in double cropping rice system in winter was the optimum multiple cropping.
