Effect Of Fertilizer And Manure Application On Soil Quality And Crops Yield In Newly-built Terraces

Terrace agriculture is effective to decrease soil erosion and increase soil C in the region characterized by a hilly landscape and limited soil resources. In this study we determined the effects of chemical fertilizers and manure on soil water content, fertilizer use efficiency and soil quality in newly built terraces on the semi-arid Loess Plateau of China.The average soil water content in the 0-100 cm soil profile before sowing over the last 4 years was greater than 40.1 mm in the MNP group than in the NP group, and was 11.3 mm higher in the M group than in the CK group. After 6 years, the soil water in the upper 200 cm of soil in the MNP and M groups was kept in balance, while significant soil water depletion reached the 140 cm soil layer in the CK and NP groups when compared to their values before sowing in 2004. The total rainfall storage values in the soil throughout the duration of the non-growing season for the CK, NP, M and MNP groups were 217.8,207.6,269.5 and 293.4 mm in the 0-200 cm soil layer, respectively. In the 0-100 cm soil layer, the rainfall storage was 58.8 mm greater in the MNP group than the NP group, and 35.2 mm greater in the M group than the CK group. Yields were highest in the MNP group, which had an average yield of field pea or spring wheat that was as high as 60% of the corresponding yields in established terraces in the region, while this value was almost 100% for potato.Soil organic carbon (SOC) and soil total nitrogen (TN) and built up fast in manure treatments, and applying fertilizer alone is not effective in increasing soil C and TN in the 6 years, it is not the lack of P reserves in all treatments when the experiment was started. At the end of 6-year experiment, the ratios of SOC to soil total N (C/N) were 11.81 in the MNP treatment and 11.89 in the M, treatment, significantly higher than those in other treatments. The C/N ratio in the NP treatment decreased with time. The ratio of soil available P to total P (AP/TP) and microbial carbon (MBC) content were significantly higher in the MNP treatment than in other treatments from the second year. There were positive correlations between MBC and MN (R= 0.846; P<0.001), MBC and AP (R= 0.950; P<0.001), and between crop yields and MN or AP for the 6 years.The overall results showed that application of manure is effective in conserving soil water, improving crop productivity and accelerating the build-up of fertility in newly built terraces on the Loess Plateau of China.