| Aiming at solving the problem of poor soil quality and low productivity of the sandy fluvo-aquic soil, the organic and inorganic soil amendment were used on soil.In this paper, the sandy fluvo-aquic soil in Henna Province was regarded as research object and harmless sewage sludge and harmless molybdenum tailings (-325 mesh) were chosen as raw materials for soil amendment, and wheat, corn and peanuts as indicative plants. This paper evaluated the improvement effects of the application of soil amendment on local sandy fluvo-aquic soil with wheat-maize and wheat-peanut crop rotation. Furthermore, we focused on the research of the influence of soil amendment on soil fertility, crop yield, soil microbial biomass carbon/nitrogen and heavy metal contents in the soil environment. In order to evaluate the improvement influence of soil amendment on soil and provide a new technology and data about the improvement of sandy fluvo-aquic soil, we filtrated a best concentration ratio between organic and inorganic soil amendment. The major results showed as follows:1. Organic and inorganic soil amendment could enhance soil quality and improve soil fertility effectively. When separately applying the organic amendment, the effect of which on soil fertility was significant with the increasing application amount. However, applying organic and inorganic soil amendment together was better than organic amendment alone. After applying the soil amendment, the contents of soil bulk density ranged from 1.24 to 1.56 g·cm-3, pH from 8.14 to 8.99, SOM from 7.92 to 17.62 g·kg-1 and TN from 7.92 to 17.61 g·kg-1. The contents of AP and AK were 17.79-70.11 mg·kg-1 and 24.55-120.18 mg·kg-1, respectively. Considered the effects of soil amendment on soil fertility indexes comprehensively, we discovered that these four concentration ratios had a better effect on soil quality. The four kinds of ratios as follows:30 t·hm-2 harmless sewage sludge and 75 t·hm-2 harmless molybdenum tailings,45 t·hm-2 harmless sewage sludge and 75 t·hm-2 harmless molybdenum tailings; 30 t·hm-2 harmless sewage sludge and 150 t·hm-2 harmless molybdenum tailings; 45 t·hm-2 harmless sewage sludge and 150 t·hm-2 harmless molybdenum tailings.2. Applying organic amendment separately or mixed with inorganic soil amendment both had a better influence on the crop yield when applying the inorganic soil amendment separately. When organic soil amendment being applied, the crop yield had a upward trend. Considered the effects of soil amendment on the crop yield comprehensively, we knew that under 45 t·hm-2 harmless sewage sludge and 75 t·hm-2 harmless molybdenum tailings, the crop yield increased. Compared with the contrast, the ratio above added 7.86% with wheat-maize rotation. Meawhile, those enhanced 7.64% with wheat-peanut rotation.3. Applying organic amendment separately or mixed with inorganic soil amendment both had a better influence on soil microbial biomass carbon (SMBC) and nitrogen (SMBN). It could reduce the contents of SMBC and SMBN when applying the inorganic soil amendment separately. When organic soil amendment being applied, SMBC and SMBN had a upward trend. Considered the effects of soil amendment on SMBC and SMBN comprehensively, we knew that under 45 t·hm-2 harmless sewage sludge and 75 t·hm-2 harmless molybdenum tailings, the contents of SMBC and SMBN increased. Compared with the contrast, the ratio above added 80.17% and 57.15% with wheat-maize rotation. Meanwhile, those enhanced 104.81% and 62.41% with wheat-peanut rotation.4. The application of organic and inorganic soil amendment would not cause secondary pollution to the soil environment and it would increase the contents of heavy mental in soil. Compared with the contrast, contents of the metals such as Cr, Ni, Cu, Zn, Cd and Pb increased 2.78-74.40%,0.00-12.97%,41.91-506.62%,3.71-76.67%, 0.00-82.35% and 0.86-40.55% respectively under the mixed applying of organic and inorganic soil amendment. The contents were below the Environmental quality standard for soils (GB15618-1995). We found that applying the 45 t·hm-2 harmless sewage sludge combined with 75 t·hm-2 harmless molybdenum tailings had the least influence on heavy metals content in soil.In conclusion, the combined application of harmless sewage sludge and harmless molybdenum tailings could not only improve sandy soil and soil quality but also promote crop yield effectively. After the combined application of these two amendment, it could not give raise to the secondary pollution caused by excessive heavy metals in soil environment. 45 t·hm-2 harmless sewage sludge and 75 t·hm-2 harmless molybdenum tailings was a best concentration ratio for improving desertification soil. |
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