The Effects Of Minimum Tillage Or No-tillage And Straw Returning On Soil Physical And Chemical Characters And Crop Annual Output

Conservation tillage is a recently-developed farming practice in China, it is becoming widely appreciated due to its unique advantages on water conservation, fertilizer conservation, improvement of quality of cultivated land and so on. Conservation tillage will get water conservation and fertilizer conservation, improve soil ecological environment of crop, affect growth and yield of crop indirectly by no-tillage or stubble retention. This study designed six treatments totally, two cropping patterns and three kinds of farming, preliminary study on the effects of conservation tillage methods on soil physical properties in hilly and annual yield of crops.1. After located experiment of six years, soil bulk density of0～20cm and20～40cm in conservation tillage decreased, respectively.0～20cm soil improved more clearly, in Wheat/Corn/Sweet Potato (Ml) mode, the soil bulk density of LS and NTS weight than the control reduceed8.87%and4.13%respectively, compared with CK; In Wheat/Corn/Soybean (M2) mode, LS and NTS reduceed6.09%and4.69%respectively, compared with CK. Conservation tillage increased soil porosity under two modes at different degree, the soil porosity of LS treatment of M1and M2increased5.20%and3.54%respectively, compared with T.2. The improvement effects of conservation tillage on soil aggregation was not clear. Analysis On the composition and stability of aggregate, founded that all treatemnts showed little difference on number of dry sieve aggregate>0.25mm and number of wet sieving water-stable aggregates of>0.25mm, compared with the traditional ways. As far as the aggregate mean weight diameter of MWD, conservation tillage were more than conventional tillage in both modes, improved the soil erosion-resistant ability, decreased the reunion of soil aggregation, compared with CK.3. Analysis on the soil water characteristic curve, founded that conservation tillage treatments were all greater than conventional tillage under M1and M2mode, by Gardner model on water characteristic curve fitting of parameters A value, no-till with straw cover and ridge sowing were greater than conventional tillage, the soil water-holding capabilities of conservation tillage was better than traditional farming methods. The specific water capacity (9) geneal trends at all suction condition of0～20cm and20～40cm was:conservation tillage methods was greater than traditional farming methods, improved the water-releasing ability.4. Study on soil infiltration capability, founded that cumulative infiltration of conservation tillages> traditional tillage methods, NTS and LS increased the accumulation of soil infiltration capacity30.75%and41.77%respectively, compared with traditional farming. The infiltration rates of all treatments at0-15min Swinged large, stabilized after15min, the initial infiltration rate varied on5.6～6.0cm/min, two modes reached a steady infiltration rate after70min. Under the two models, LS had the highest steady infiltration rate, M1:1.18cm/min, M2:0.80cm/min, respectively. Comparing with traditional farming, the stable infiltration rates of NTS and LS at M1model increased0.17and0.31m/min, respectively, NTS and LS at M2model increased0.15and0.27m/min, respectively, the stable infiltration rate of M1mode was slightly higher than the M2model. 5. The test results showed that conservation tillage increased soil pH, soil organic matter except the CT at M1model treatemnt with highest organic matter content, the other conservation tillage treatemnts were greter than the traditional farming, and achieved very significant levels. Under M2mode, NTS and LS were higher than conventional tillage, increased12.39%and3.85%respectively. In General, conservation tillage increased soil nutrients, total N and K of two mode showed that NTS>CT>LS, NTS at M2mode had highest total N content; total P:M1model showed that NTS>LS>CT, M2model showed that NTS>CT>LS. UnderTwo modes, alkaline hydrolytic nitrogen showed that LS>NTS> CT, compared with CK, two kinds of conservation tillage increased available phosphorus; At M1mode, the change of available potassium showed that NTS increased35.67mg/kg than CT, LS and CT had little difference, at M2mode, NTS increased22.62mg/kg than CT, LS decreased30.85mg/kg than CT. The soil cation exchange capacity at two kinds of conservation tillage were significantly higher than traditional farming, showed that NTS>LS>CT.6. Analysis on yield data of six years, founded that different crop yields increased under all treatments as year prolonged, annual outputs also increased with prolonged period, conservation increase rate was greater than traditional tillage relatively. Under Ml mode, the three crops showed that NTS>LS>T. Compared with conventional tillage, the average yield of wheat in NTS and LS increaed1581.45and75.75kg/hm2respectively; The average yield of maize increased42.37%and17.48%respectively; The average yield of sweet potato increased2269.65and1738.95kg/hm2respectively, compared with CK. Under M2model, conservation tillage decreased the yield of wheat, the yield of maize in NTS increased, the yield of soybean in LS increased13.89%, and in NTS decreased, compared with CK.