| Shaanxi weibei Dry-land located in southeastern semi-humid region of loess plateau,annual rainfall is only 500~600 millimeters,and 60% of precipitation distributed mainly in July to Septembe,dry farming is main in agricultural production,drought is the biggest limiting factor in local agriculture. The biggest task for conservation tillage is to reduce disturbance of soil and improve soil ability to soil water retention through minimum and no-tillage measures,thus attaining the purpose of increasing the yields and economic returns. This experiment design two factors split block experiment fertilizer treatments(balanced fertilization,traditional fertilization and low fertilization) for main treatment,tillage treatments as no-tillage,sub-soiling and deep plowing for secondary treatment,and discussed the optimal combination of different fertilizer treatments and tillage and rotational tillage treatments,to provide a scientific basis for winter wheat yields and economic returns of Weibei highland. Based on the three years field experiment,there are five conclusions as following:1.Effects of conservation tillage and its rotation on water storage in wheat fieldNo-tillage and sub-soiling had better soil moisture conservation effects than deep plowing in summer fallow. During summer fallow of three trial, average soil water content in 0-300 cm soil layer of no-tillage and sub-soiling treatments were 0.6 and 0.5 percentile higher than that of deep plowing,and average water storage increased 24.2 mm and 21.5mm, respectively. During winter wheat growth period, average water storage in 0-200 cm soil layer of no-tillage and sub-soiling treatments increased 17.7 mm and 14.4 mm, respectively, compared to deep plowing treatment in two wheat growth seasons; From the rotation tillage perspective continuous no-tillage most beneficial to soil water storage, in the end of summer fallow soil water content of continuous no-tillage(NP2007-NP2008-NP2009-NP2010) is highest,soil water content is 13.72%,plowing and no-tillage rotation tillage(P2007-NP2008-P2009-NP2010) takes second place,soil water content in the end of summer fallow is 13.70%. Soil water content of continuous plowing(P2007-P2008-P2009-P2010) is minimum about 12.73%. Soil water content of continuous no-tillage was 0.02 percentile higher than that of plowing and no-tillage rotation tillage(P2007-NP2008-P2009-NP2010) and was 0.99 percentile higher than that of continuous plowing(P2007-P2008-P2009-P2010).2.Effects of conservation tillage on yield and incomes in wheat fieldSub-soiling combined with balanced fertilization was the highest yield treatment among all treatments. Its average yield in two wheat production seasons was 5 033.1 kg/hm~2,and it was 5.5% and 6.3% higher than deep plowing and no-tillage combined with balanced fertilization treatments,respectively. No-tillage combined with balanced fertilization was the highest economic benefit treatment among all treatments. Its average net return in two wheat production seasons was 5 553.7 yuan/hm~2, and it was 3.3% and 9.2% higher than sub-soiling and plowing combined with balanced fertilization,respectively. This study comprehensively concluded that considering soil water retention effect,wheat yield increment and economic benefit,sub-soiling combined with balanced fertilization treatments were the preferable conservation tillage and fertilization combination treatments on continuous cropping of dryland wheat field in Weibei Highland.After three years of"2007-2010"experimental study No-tillage and sub-soiling rotation tillage combined with balanced fertilization was the highest yield treatment among all rotation tillage treatments. Its yield in three wheat production seasons was 4259.33 kg/hm~2,continuous sub-soiling takes second place, Its yield in three wheat production seasons was 4257.69 kg/hm~2,continuous plowing with low fertilization was minimum, Its yield in three wheat production seasons was 3256.56 kg/hm~2.3.Effects of conservation tillage on WUEThe WUE of Sub-soiling combined with balanced fertilization treatments was highest,plowing combined with balanced fertilization treatments took second place and No-tillage combined with low fertilization was minimum. The average WUE in two wheat production seasons was 17.33 kg/(hm~2·mm),15.59 kg/(hm~2·mm) and10.35 kg/(hm~2·mm) respectlively.4.Effects of conservation tillage on soil fertilizationThe study on experiment from 2007-2009 shows that soil organic matter content in 0~60cm soil layer of sub-soiling and No-tillage were higher than plowing,and it was 4.9% and 7.5% higher than plowing, respectively. Because sub-soiling and No-tillage raised soil organic matter content in 0~20cm soil layer,soil organic matter content in 40~60cm soil layer was lower than plowing. Nitrogen content of No-tillage and sub-soiling treatment were higher than plowing treatment and it was 5.3% and 1.1% higher than plowing, respectively. The content of total phosphorus in soil of No-tillage and sub-soiling treatment were higher than plowing treatment and in two wheat production seasons its average content was 6.1% and 5.3% higher than plowing, respectively. Available potassium content of No-tillage was higher than sub-soiling and plowing and in two wheat production seasons its average content was 6.1% and 5.3% higher than sub-soiling and plowing, respectively. Alkali-hydrolysable nitrogen content of No-tillage was higher than sub-soiling and plowing and it was 21.1% and 11.6% higher than sub-soiling and plowing,respectively. Available potassium content of No-tillage was higher than sub-soiling and plowing and in two wheat production seasons its average content was 6.1% and 11.7% higher than sub-soiling and plowing,respectively. Potassium content of No-tillage was higher than sub-soiling and plowing and in two wheat production seasons its average content was 2% and 7% higher than sub-soiling and plowing, respectively. So No-tillage treatment compared to sub-soiling and plowing is helpful to sustain soil nutrition. Available phosphorus content in 0~60cm soil layer of continuous No-tillage and plowing and No-tillage rotation were higher than continuous plowing,and it was 31.6% and 20.1% higher than continuous plowing,respectively. Available potassium content in 0~60cm soil layer of No-tillage and sub-soiling rotation and continuous No-tillage were higher than continuous plowing,and it was 30.8% and 25.8% higher than continuous plowing, respectively. Available nitrogen content in 0~60cm soil layer of No-tillage and sub-soiling rotation and continuous No-tillage were higher than continuous plowing,and it was 25.5% and 14.4% higher than continuous plowing,respectively. Soil organic matter content in 0~60cm soil layer of continuous No-tillage and No-tillage and sub-soiling rotation were higher than continuous plowing,and it was 34.2% and 31.3% higher than continuous plowing,respectively. So continuous No-tillage is good for increasing soil available nutrient content as well as No-tillage and sub-soiling rotation. |
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