Effect Of Different Tillage On Soil Physical And Chemical Properties And Crop Growth In The Dryland Of South Ningxia Region

The study set the experiment for conservation tillage technology of different rotation systems in Guyuan experimental station of Northwest A & F University in 2007-2009, in this study, we analysed the effect of different rotations on soil physical and chemical properties and crop growth status, then, selected the tillage effectiveness of different farming modes. The main results were showed as follows:1. Two years experimental study showed that rotation could decrease soil bulk density. Soil bulk density decreased significantly in 0～20cm of autumn cultivation test, among them, S₀₇→S₀₈,N₀₇→N₀₈,S₀₇→N₀₈ and N₀₇→S₀₈ decreased 3.1%,0.8%,2.3% and 1.6% than CK (P>0.05), there were no significant differences between CT1 and rotation treatment in 20～40cm and 40～60cm.. Soil bulk density decreased also most significantly in 0～20cm of summer cultivation test, among them, S₀₇→N₀₈ and N₀₇→S₀₈ decreased 3.1%,1.5% than CT2 (P>0.05), there were no significant differences between CT2 and rotation treatment in 20～40cm and 40～60cm.2. After 2 years of the fall tillage treatment, before millet planting in 2009, the total water storage in 0～80cm soil layer was significant different than CK, compared to CK, the total water storage in 0～80cm soil layer of S₀₇→S₀₈,N₀₇→N₀₈ and N₀₇→S₀₈ treatments increased by 51.41mm,20.03mm and 44mm(P<0.05), S₀₇→N₀₈ treatment showed no significant difference when compared with CT1. In the summer season cultivation experiments, before wheat planting in 2008, compared to CK, the total water storage in 0～200cm soil layer of N₀₇→S₀₈ and S₀₇→N₀₈ treatments increased by 16.38mm and 24.61mm(P<0.05)3. After 2 years of the fall tillage, compared to CT1, the soil organic matter and total N in 0～40cm layer of S₀₇→S₀₈ treatment was 5.4% and 9.6% higher than CT1, respectively, N₀₇→N₀₈ and N₀₇→S₀₈ treatments significantly increased the available K content in 0～20cm soil layer, those were 14.9% and 23.3% higher than CT1; respectively, for other nutrient, there were no significant differences between CK and other treatments. Across the summer season cultivation experiments, the soil organic mater and total K in 0～40cm layer of N₀₇→S₀₈ treatment was 5.2% and 9.6% higher than CT2(P<0.05); respectively, the total N in 0～40cm layer of N₀₇→S₀₈ and S₀₇→N₀₈ treatments was both 7.58% higher than CT2(P<0.05), for other nutrient, there were no significant differences between CK and other treatments.4. Two years rotation experiment showed that rotation systems could impact crop height and dry biomass accumulation. In autumn cultivation test, during millet maturity in 2009, the plant height of S₀₇→S₀₈ and S₀₇→N₀₈ treatments was 6.5cm and 3.1 higher than CT1, the differences were significant, but little differences among N₀₇→N₀₈, N₀₇→S₀₈ and CK; during millet maturity, the dry biomass of S₀₇→S₀₈,S₀₇→N₀₈ treatment showed no significant differences when compared with CT1; the dry biomass of N₀₇→N₀₈ and N₀₇→S₀₈ treatment were lower 17.8% and 29.6% than CK respectively, the differences were significant. In summer cultivation test, during wheat maturity in 2009, the wheat height of S₀₇→N₀₈ treatment was 4.6cm higher than CT2(P<0.05), but little differences between N₀₇→S₀₈ and CT2; During wheat maturity, the dry biomass of S₀₇→N₀₈ treatment was the maximum, but no significant differences between CK and other treatments.5. After 2 years of the fall tillage, at the time of millet harvest in 2009, the spikelet numbers of S₀₇→S₀₈ treatment was 13.2% higher than CT1, the difference was significant, but the other treatments have no significant differences compare with CT1; the spikelet weight of S₀₇→S₀₈ and S₀₇→N₀₈ treatments were significantly higher than CK, while N₀₇→N₀₈ and N₀₇→S₀₈ treatments were significantly lower than CK, for 1000-grain weight, there were little differences between CK and other treatments.. In summer cultivation test, at the time of wheat harvest in 2009, for spikes number per hectare, grains per spike and 1000-grain weight, there were no significant differences between CT2 and other treatments.6. Two years study showed that, rotation could increase the number of macro aggregates. In autumn cultivation test, at harvest in 2009, the content of>0.25mm elastic-stable aggregate in 0～10cm and 10～20cm soil layer of all the rotation treatments were 20.0% and 9.9% higher than CT1,the differences were significant, little difference were in 20～30cm and 30～40cm soil layer; the content of>0.25mm elastic-stable aggregate in 0～10cm, 10～20cm and 20～30cm soil layer of all the rotation treatments were significantly increased compared with CT1, the average increase were 31.9%,14.2% and 23.1%, respectively. In summer cultivation test, at harvest in 2009, the content of>0.25mm elastic-stable aggregate in 0～40cm soil layer of all the rotation treatments were significantly higher than CT2, the average increase was 14.7%. while the content of>0.25mm elastic-stable aggregate in 10～20cm and 20～30cm soil layer of all the rotation treatments were significantly higher than CT2, the average increase were 51.9% and 34.3%, respectively, there were little difference in 0～10cm and 30～40cm soil layer among treatments.7. Two years study showed that rotation could increase crop yields and improve crop WUE. In autumn cultivation test, compared to CT1, the millet yield of S₀₇→S₀₈ and S₀₇→N₀₈ increased by 3.5% and 6.7%, while the WUE of S₀₇→S₀₈ and S₀₇→N₀₈ treatments increased by 14.5.0% and 17.7% compared with CT1, the millet yield of N₀₇→N₀₈ and N₀₇→S₀₈ treatments were significantly lower 20.6% and 22.5%, the WUE N₀₇→N₀₈ and N₀₇→S₀₈ were 8.1% and 17.7% lower than CT2. In summer cultivation test, compared to CT2, the wheat yield of S₀₇→N₀₈ and N₀₇→S₀₈ increased by 5.4% and 2.6%, while the WUE increased 8.9% and 17.0%.