Research On Productivity, Ecological Environmental Effect And Sustainability Evaluation Under Paddy-upland Rotation Systems

Adjustment of agricultural structure is a breakthrough to effectively solve the problem of agricultural ecological and farmers’ income, and the adjustment of farming is a key for agricultural structure adjustment. Increase cropping index and rational fertilization are important measures to improve the productivity of crops in paddy fields. Upland rotation is the basic method to improve cropping index, is one of the major farming systems in southern China, and plays a crucial role in the crop high-yield, maintaining soil fertility and soil improvement. In this study, on the basis of the long-term experiment, by two consecutive years of field trials, the researchers evaluated crop productivity and sustainability assessment under upland rotation system in paddy fields. The results are as follows:1. Upland rotation pattern could improve rice growth dynamics and rice yield,including the two cropping patterns of milk vetch- rice- rice and mixed green manure-rice- corn‖sesame performed better. From the perspective of crop growth dynamic, “milk vetch- rice – rice” and “ryegrass- rice- corn‖soybean” can reduce ineffective tillers,ensure more effective tiller and increase spike rate, and are more favorable for rice growth.Winter green manure patterns have a certain role on improving the content of chlorophyll,including cropping pattern of milk vetch- rice – rice was the most significant.2. The upland rotation patterns of ryegrass- rice- rice �' ryegrass- rice- corn ‖soybean help to improve soil fertility, promote the nutrient accumulation and absorption in paddy fields. Upland rotation patterns increase the number of soil bacteria, azotobacter,fungi, actinomycetes, but also make crops get a full nutrients. These are beneficial to crop growth and development, in which upland rotation patterns of “mixed green manure- rice-corn ‖ sesame” performed best. The continuous cropping mode “green manure- rice –rice” is significantly larger than the other rotation modes for microbial biomass carbon and nitrogen, respectively an increase of 12.12%-76.19% and 11.84%- 42.68%, while “mixed green manure- rice- corn ‖ sesame” is the best performance in terms of soil enzyme activities.3. Treatment of milk vetch- rice- rice can obtain a higher biomass than other patterns.It could grow rapidly in the early stages of rice, lay the foundation for dry matter accumulation, ensure population biomass increase with higher yield potential. Rice plants nitrogen rate under green manure rotation decreased with the growth process, the maximum tillering stage, the minimum maturity. Under green manure rotation N uptake ofrice plants increased with growth process, up to a maximum maturity. In tillering, booting,heading and maturity treatment of milk vetch- rice- rice are highest, but rapeseed- rice-rice minimum. N periodic accumulation and its ratio to total in the heading to maturity was minimum, maximum before tillering under green manure rotation system.4. The treatment of green manure- rice- rice on paddy weed density had a significant effect on inhibiting weeds than other processings, followed by the mixed green manure-rice- rice and rapeseed- rice – rice. The treatment of ryegrass- rice- rice was the lowest.There were seven families 11 kinds of weeds in the survey area, while the number of barnyardgrass, benn grass, dwarf arrowhead and cattle blankets accounts for 80.84% of the weed. The weed species richness of ryegrass- rice- rice is maximum, but milk vetch- rice- rice minimum. The evenness index of green manure- rice- rice is higher than other treatments, but the difference was not significant. It indicated that in this way the structure of weed community has changed a lot, improves uniformity, thereby decreases the harm of dominant species of weeds in paddy field.5. Under upland rotation the four treatments of total energy input and output values are expressed as rapeseed- rice- rice�'rapeseed- rice- corn‖peanut> ryegrass- rice- rice�'ryegrass- rice- corn ‖ soybean = mixed green manure- rice- rice �' mixed green manure- rice- corn‖sesame> milk vetch- rice- rice�' Chinese milk vetch- rice- rice.The sustainable energy index of mixed green manure- rice- rice �' mixed green manure- rice- corn‖systems sesame is highest, 0.0315, and rapeseed- rice- rice �' rapeseed-rice- corn‖peanut lowest, is 0.0148. In this study, sustainability index of four kinds of cropping systems are below one. The environment has brought a lot of pressure, a large amount of non-renewable resources utilization, resulting in a higher rate environment load,resulting in lower sustainability index. The cropping systems of “mixed green manure-rice- rice�' mixed green manure- rice- corn‖sesame” is worth promoting.