| Straw concentrated ditch-buried returning field is from Nanjing Agricultural University new technology system of straw and soil tillage combination with rice-wheat rotation system in recent years. The technique is based on the wheat and rice two cropping system of high grain yield, straw yield, soil tillage layer shallow, stubble convergence tight, which had no good effect of plenty of straw returning field on the seedling and ecological environment. Immediately ditching using machine in the field according to a certain distance, straw-buried and covering soi after crop harvest of each season, which make soil surface clean and the drainage and waterlogging reduction function of straw ditch, which ensure comprehensive function of the full amount of straw returning safety and convenient soil tillage and seeding and improve soil drainage and beneficial to drought resistance on rice and wheat growth and effectively and which increase soil carbon sequestration and inhibi pest infection cycle from straw and reduce the loss of soil nutrient. Straw concentrated ditch-buried returning field through five years can realize the whole field of deep soil rotation, effectively improve the overall structure of soil tillage measures.This study with field experiment was mainly about:①Resultt of machine ditch and the effect of straw concentrated ditch-buried returning field②Analysis on carbon balance from farmland with straw concentrated ditch-buried returning field using machine ditch③Analysis on economic benefit of straw concentrated ditch-buried returning field using machine ditchThe main conclusion were as follows:1. Straw concentrated ditch-buried returning field using machine ditch have wide popularization valueTop width and bottom width of trapezoidal ditch were about35.00,19.20cm and35.50, 20.50cm, the average depth of ditch were19.50,29.90cm and19.76,28.74cm, distance of centralized throwing soil were38.00,41.00cm and44.14,44.19cm, thickness of centralized covering soil were11.45,17.17cm and12.67,16.99cm individually or using machine ditch with the depth of20,30cm during the wheat and rice season, at the same time, broken rate of soil were both more than90%and88%. Oil consumption was143.59,158.17ml/m3and101.94,108.54ml/m3, respectively. In the wheat season the drainage and waterlogging reduction function of straw ditch were similar as common drainage ditch. Decrease amplitude of water content in straw ditch for D2and D3were larger than that of CK, and D3had better effect of waterlogging reduction than D2. Straw concentrated ditch-buried returning field using machine ditch with suitable ditch depth had no effect on the level whole in farmland in the rice season.The germination and growth of rice and wheat crop on ditch-buried were both better than that of CK. The ditch performance was reliable and excellent, and the ditch can meet straw-buried and covering soil requirements. Ditch-buried had drainage function, no bad effect on the seedling and the level whole in farmland and growth of wheat.Straw concentrated ditch-buried returning field using machine ditch was feasible and have wide popularization value2. Straw concentrated ditch-buried returning field using machine ditch reduce carbon emission and increase soil carbon sequestrationThe carbon emission from agricultural inputs under CK, D2and D3was9018.19,6459.90,7162.86kg/(hm2-a) from rice-winter wheat rotation system, soil carbon storage in0-28cm top soil was8375.98,15854.42,10954.36kg/(hm2-a), and the crop carbon uptake was10912.42,12863.95,12585.51kg/(hm2-a), respectively. Net C emission was-10270.21,-22258.47,-16377.01kg/(hm2-a), respectively. Compared with CK, the relative net C emission under D2and D3was-11988.26,-6106.80kg/(hm2-a). The decrement of the C emission from agricultural inputs under D2and D3(2558.29,1855.33) kg/(hm2·a) was8.91%,7.88%of the increment of Carbon sequestration(28718.37,23539.87kg/(hm2·a)) during rice-winter wheat rotation system. Straw concentrated ditch-buried returning field using machine ditch had a greater contribution than CK in the atmospheric carbon emission reduction and carbon sequestration, its priority order was D2>D3>CK.3. Straw concentrated ditch-buried returning field using machine ditch with suitable ditch depth can bring higher economic total benefitsCost input of material under CK, D2and D3was15423.80,18886.89,21785.56yuan/(hm2.a), while the total income and economic benefit was43038.24,47890.57,45721.98 yuan/(hm2.a) and27614.62,29203.7,24136.43yuan/(hm2.a), the value of ecosystem services and ecological compensation was37960.75,51621.85,40632.34yuan/(hm2.a) and197.68,770.97,525.21yuan/(hm2.a), which economic total benefit was27812.3,29974.66,24661.64yuan/(hm2.a) during rice-winter wheat rotation system, respectively. Straw concentrated ditch-buried returning field using machine had a greater cost input than that CK, through the establishment of ecological compensation mechanism for ecological compensation, straw concentrated ditch-buried returning field using machine with the depth of20cm had the best economic revenue and net profit. Under the no effect of the actual crop yield, straw concentrated ditch-buried returning field using machine ditch with suitable ditch depth can bring higher economic totalbenefits than that of CK. |
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