The Effects Of Different Combinations Of Fertilization On The Relationship Between Soil Water And Nutrients And On The Yields, Loess Plateau Area, China

Sustainable management of soil ecosystem is one of the main ways to conserve sustainable development of agriculture, and which is the most important research focus most researchers paid to recently. Soil moisture is the most important factor limiting agricultural production. This research is based on the previous studies, conducts sustainable management in soil ecosystem through eight different combinations of fertilization, that are: CT (none fertilizer applied always);N(nitrogen fertilizer applied only);P(phosphorous fertilizer applied only);NP(nitrogen and phosphorous fertilizer are applied together);Org(organic fertilizer applied only);NOrg(nitrogen and organic fertilizer are applied together);POrg(phosphorous and organic fertilizer are applied together);NPOrg ( nitrogen, phosphorous and organic fertilizer are applied ), this research was conducted on the Plateau Loess Experimental Station, Lanzhou University, in zhonglianchuan area, Yuzhong, Gansu Province.(l)The correlation of soil water storage at harvesting in 2m soil profile 2003a and pea yield 2003a was R=0.134, expressing positive relationship trend, and the correlation of soil water storage in 2m soil profile and wheat yield 2004a at planting was R=0.468, which was R= 0.344 at harvesting, and the relationship between soil water storage in 2m soil profile and potato yield, 2005a, was R=0.795*, p=0.05, that is significantly related, which was R=0.609 at harvesting, 2005a, positive relation trend.(2)The results of this experiment illustrate the dynamics of the content of Light Fraction of Organic Carbon (LFOC), the concentration of LFOC in 20cm soil profile. It indicates that, LFOC has no significant change in NP and NPOrg treatments. The treatments with organic fertilizer applied have better stability of LFOC than those with single chemical fertilizer applied. So, we can say sustainable agriculture asks for sustainable managements in soil ecosystem without disturbing the balance of organic and inorganic factors about natural soil ecosystem. This research find the change of LFOC in 20cm soil profile was most dynamic than other fertilization treatments, NPOrg was the most stable treatment.(3) Soil Microbial Biomass Carbon contents of these eight different fertilizer combinations of CT, N, P, NP, Org, NOrg, POrg, NPOrg in 20cm soil profileare 109.2, 150.0, 159.7, 133.6, 112.3, 149.2, 153.4, 151.0mg/kg at planting 2004a;118.4, 162.4,155.5, 159.4, 126.6, 177.0, 161.6, 189.9mg/kg at planting 2005, the relationship between MB-C content in 20cm soil profile and the yield of this year is R2004 = 0.655, R2005 = 0.756* respectively..(4) The correlation analysis between soil 2m profile moisture, soil organic carbon in surface soil profile 20cm and the yields tell us: the soil profiles from 0 to 60cm are negative related with production at harvesting, and the correlations between soil water content of soil profile from 60 to 120cm are positive, 2003~2005a. And that are postive relationship between soil water moisture in 0~ 120cm soil profile and the yield of pea 2003a, wheat 2004a, and potato yield 2005a at sowing.(5)The change of soil organic carbon, for example LFOC, can represent the trend of soil water and fertilizer loss from the farmland. So the soil ecosystem of NP and NPOrg treatments are the most stable and the highest function capacity. CT is not the sustainable mode of agriculture because it has the better soil water condition but the loss from this experimental soil ecosystem is startling and the soil of which has the worst stability. So, the crop production of CT is lowest, NPOrg has the highest crop production. And the yield is stable and high in NPOrg treatment but the opponent in CT.