| Farming methods, mainly as minimal tillage in the area of drought, low fertility and sandy chestnut soil in Inner Mongolia can help to hold water and fertilizer and reduce carbon emissions. In this paper, based on planting oats (2013), rape (2014), the typical grain crops of the region, in four different farming methods, namely shallow depth (QS), a light spin (QX), subsoiling (SS) and bare deep pine (LSS) traditional tillage (CT) as controls, we study their influence on soil organic carbon, soil physical properties and biological characteristics of dry farmland and yield components while we preliminary clarify their correlativity and correlation. The results of two consecutive years are as follows.(1) Different farming methods can improve some of soil physical properties. Compared with CT. QS and QX significantly reduced soil bulk density in 2013 and all these three farming methods increased the>0.25mm soil aggregates content in 2014. Different farming methods improved soil moisture to varying degrees within two years, especially influencing on 0-50cm soil horizon in the pod period of rape. Compared with CT, QS, QX, SS and LSS increased the soil moisture content by 42.92%.15.59%, 39.88% and 44.92% respectively. After harvesting, soil moisture content of test field was higher than CT. and the performance was SS> QS> QX> LSS> CT in 2014.(2) Different farming methods can significantly increase the content of soil organic carbon fractions, benefiting carbon sink. Four farming methods increased the content of soil organic carbon to varying degrees within two consecutive years. Specifically, there was a 78.82%-89.77% increase in soil organic carbon content in 2014, which was very significantly positive correlated with soil carbon density, bulk density, the activities of both urease and sucrase. Compared with CT, all farming methods dramatically increased soil carbon density (1.80-2.57 times on average) and the content of soil recombinant organic substance (1.72-2.36 times on average) of 30-50cm soil horizon in the flowering and pod period. QS, QX, SS and LSS significantly increased the activity of soil organic carbon content to some extent, especially influencing on 0-10cm soil horizon in flowering period and 30-50cm soil horizon in pod period of rape. Meanwhile, different farming methods significantly improved the content of the soil easily oxidized organic carbon, soil microbial biomass carbon and light fraction organic carbon, and three kinds of active organic carbon show a very significant positive correlation, and the correlation coefficients are R= 0.634, R= 0.777 and R= 0.731.(3) Different farming methods improve soil biological characteristics. Different farming methods increased the content of soil microbial biomass carbon and nitrogen within two years especially in 2014. Compared with CT. SS increased more by 15.81%-25.63% and 60.69%-58.05% each in 2014. Furthermore, these soil microbial biomasses were very significant positive correlated of different farming methods. The activities of soil catalase. urease and alkaline phosphatase were significantly increased, and a very significant positive correlation between urease and invertase and alkaline phosphatase improve soil invertase activity to some extent. Soil catalase and alkaline phosphatase also showed a significant positive correlation. Different farming methods reduced soil respiration rate with the advancing age, especially SS was significantly reduced soil respiration rate in 2014 compared with CT, and was very significant positive correlated with the soil temperature, urease. light fraction organic carbon, recombinant organic carbon and microbial biomass while was significant positive correlated with soil invertase, alkaline phosphatase. total organic carbon, microbial biomass carbon.(4) Different farming methods improve grain yield. Compared with CT, different tillage systems significantly improved yield of oats in 2013, while in 2014, only SS significantly increased yield of rape,75.38% higher than CT. Based on the correlation analysis of soil organic carbon components and microbial biomass, grain yield is significantly positive correlated with soil organic carbon, easily oxidized organic carbon and microbial biomass carbon content, and is very significantly positive correlated with light fraction organic carbon, recombinant organic carbon and microbial biomass nitrogen.In conclusion, SS of different farming methods improve some of soil physical properties, increase the contents of soil organic carbon contents and soil microbial biomass. increase four soil enzymes activity, reduce soil respiration rate and significantly increase grain yield, which means these farming methods are suitable for the area of Yinshan Mountain. |
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