| Dry land terrace is an effective measure to increase grain yield per unit area.The new terrace must be fertilized by soil to increase yield.The dynamic characteristics of soil quality and crop yield were studied by applying different fertilizer treatments on newly constructed dry land terraces in May 2002.The beginning of August 2003,the newly built terraces had four treatments:(1)blank control(CK): without any fertilizer;(2)nitrogen\phosphorus fertilizer treatment(NP): the annual application of 70 kg/ha nitrogen and 15.7 kg/ha phosphorus,nitrogen fertilizer and phosphorus fertilizer collocation;(3)organic fertilizer treatment(M): the annual application of farmyard manure(2003-2006 annual 20t/ha,2007-2016 annual 10 t/ha);(4)nitrogen and phosphorus fertilizer plus organic manure(MNP): the annual application of 70 kg/ha nitrogen and 15.7 kg/ha phosphorus,the annual application of farmyard manure(2003-2006 annual 20t/ha,2007-2016 annual 10 t/ha),nitrogen fertilizer\phosphate fertilizer and organic manure application of collocation.The test applied manure is mainly sheep manure,the average nutrient content are as follows: organic carbon 250.0 g/kg,total nitrogen 10.0g/kg,total phosphorus 0.84 g/kg,available phosphorus 0.16 g/kg,inorganic nitrogen 0.08 g/kg;The content of nitrogen is about 46% in urea,The content of phosphate in superphosphate phosphorus pentoxide is about 16%.Applying nitrogen,phosphorus fertilizer and manure in October after each year's harvest.Three main crops in semi-arid area of Loess Plateau were selected.They were planted with rotation of pea,spring wheat and potato.The main results are as follows:1.The water storage of 4 treatments at 0-200 cm soil layer decreased significantly after 13 years of tillage.The soil water storage with organic manure(M and MNP)was significantly higher than that of the control(CK)and single nitrogen\phosphate treatment(NP)in the 0-100 cm soil layer.The soil water storage of organic manures(M and MNP)was significantly lower than the two treatments without organic fertilizer(CK and NP)in the 100-200 cm soil layer at the end of the trial.2.Dry land teerace applied organic fertilizer(M and MNP)not only can rapidly increase content of soil light fraction organic carbon and total organic carbon and total nitrogen,but also can increase the total organic carbon and total nitrogen in deep soil;Only applying nitrogen and phosphorus fertilizer(NP)had limited effects on the content of light organic carbon,total organic carbon and total nitrogen in surface soil,there were no significant effects on total organic carbon and total nitrogen in deep soil;Applying organic fertilizer(M and MNP)and nitrogen and phosphorus fertilizer(NP)can rapidly increase total phosphorus and available phosphorus in surface soil,only applying nitrogen and phosphorus fertilizer(NP)could not improve the content of total phosphorus and available phosphorus in de ep soil;Applying organic fertilizer treatments(M and MNP)can increase the total phosphorus content in deep soil,and have no significant influence on the content of available phosphorus in deep soil.3.The combined application of organic manure and nitrogen and phosphorus fertilizer can maximize crop yield.Non growth season precipitation,growth season precipitation,organic carbon,total nitrogen,total phosphorus,available phosphorus content can affect crop yield.The results of path analysis showed that soil organic carbon content had a greater impact on the yield of pea and spring wheat;Soil total nitrogen content had significant effects on potato yield;The total phosphorus content of soil also affected the yield of spring wheat;Soil available phosphorus content had significant effects on the yield of pea,spring wheat and potato;The non growth season precipitation was negatively correlated with the yield of spring wheat and potato,there was a significant positive correlation between growth season precipitation and yield of pea,spring wheat and potato. |
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