| Corn,millet,beans,soybeans,potatoes and cabbage were used as experiment materials to compared and analysis the differences among output,water consumption,water use efficiency and soil moisture dynamics under 26 kinds of rotation combination in semi-arid regions for further screening optimal rotation combinations to adapt to local agricultural production giving consideration of economic and ecological benefits.The results showed as follows:(1) In crop rotation system,the dynamic changes of soil moisture had similar tendency for the same crop in the same year,but the consumption of soil moisture showed enormous differences on time and space due to the different effection of previous crop.Relatively,a variation of soil moisture also showed significant differences while different crop were planted in the same year.On the whole,all of rotation system had similar change tendency,was little early and high in the Mid-term while decreased at maturity.(2) In 2014,economic output of beans and cabbage decreased significantly due to the reduction of the precipitation and the prices of vegetables,as a result,output of all of rotation system reduced.In this case,beans,potatoes and corn had been less affected,so that the volatility of output and yield in these related system was relatively small.(3) In crop rotation system,the equivalent production in 2014 in descending order was:cabbage,corn,beans,soybeans,potatoes,and the yield increased sharply while cabbage was added to the rotation system.Among them,optimal rotation combination was corn-potato-bean-cabbage whose yield was 4549kg/666.7m2 which significantly higher than other combination.(4) By analyzing the economic output value of rotation system,beans had the highest value in 2014 which was 5000yuan/666.7m2,while the one of cabbage was only about 1000yuan/666.7m2.In system,the rotation combination which had the highest output value was millet-bean-bean-bean whose value reached 18199yuan/666.7m2,followed by corn-Bean-cabbage-potato and millet-bean-cabbage-potato,their value were both more than 13000yuan/666.7m/.(5) By analyzing the water consumption of rotation system,the water consumption in 2014 in descending order was:corn,cabbage,potatoes,soybeans,beans.Difference of maximum and minimum of water consumption was more than 100mm.The combinations which had lower water consumption corn-cabbage-potato-soybeans,millet-cabbage-potato-soybeans and corn-cabbage-soybean-potatoes,their mean of water consumption were all about 1365mm.The combinations of higher water consumption whose mean were more than 1560mm were millet-corn-corn-corn,millet-soybean-cabbage-potato and corn-corn-corn-corn.(6) By the analysis of water use efficiency in crop rotation system,the water use efficiency in 2014 in descending order was:cabbage,beans,potatoes,corn and soybeans. The combinations which had higher water use efficiency were millet-cabbage-cabbage-cabbage and corn-cabbage-cabbage-cabbage. Their mean were both higher than 63kg/mm·666.7m2,followed by corn-potato-bean-cabbage,millet-bean-potato-cabbage,corn-bean-potato-cabbage whose mean were about 37kg/mm·666.7 m2.Corn-soybean-soybean-soybean and millet-soy-soy-soy had the lowest water use efficiency which were just about 3kg/mm·666.7m2.(7) In summary,taking consideration of economic and ecological benefits,we ultimately selected optimal rotation combinations to adapt to local agricultural production had corn-bean-cabbage-potato,corn-potato-cabbage-soybeans,corn-potato-bean-cabbage,corn-soybean-cabbag-potato and millet-bean- potatoes-cabbage. |
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