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Nitrogen Regulation of Sandy Soil by Straw Modified Materials

Author: LiuShuangYing
Tutor: ZhaoXiuLan
School: Southwestern University
Course: Environmental Engineering
Keywords: Straw improved materials PAM Adsorption and desorption Leach Nitrogen
CLC: S153.6
Type: Master's thesis
Year: 2010
Downloads: 72
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Abstract

Sandy soil coarse particles, the lack of organic matter, there is soil particles dispersed, ill-structured, low soil nutrient content, soil moisture and nutrient holding capacity and weak, not only makes the low productivity of the soil, but also applied into the soil nutrients with water wastage pollution of the water environment, improve sandy soil improved performance is important for retaining water and fertilizer. In this thesis through culture experiments, the adsorption desorption experiment and soil column leaching simulation test, straw composite improved materials - bentonite-PAM (straw composite improved material) in different proportions, the dosage and the incubation time of the sandy soil mineral nitrogen Nitrogen adsorption and desorption characteristics leaching characteristics, the main conclusions are: (1) soil NH4-N and N03'-N content PAM dose of obvious, but by the amount of straw composite improved materials and incubation time is significant. Straw composite improved materials applied 2g/kg 5g/kg and 10g/kg treated soil NH4-N content than CK soil were an average increase of 7.98%, 53.87% and 80.80%, N03'-N content than CK average 30.19%, 79.23% and 115.46%, respectively, showed increasing straw improved materials applied to the amount of soil NH4-N and N03 - Occurrence of N content increased trend; cultured 0-60d soil NH4-N and N03'-N content gradually improve as the incubation time. 60d reached the maximum, and thereafter reduce with prolonged incubation time. (3) adsorption isotherm tests showed the soil NH4 adsorption stage of the rapid adsorption and slow adsorption stage, its turning point with the added amount of straw composite improved materials and PAM proportion contained vary. Langmuir equation could well reflect the soil of each treatment NH4 adsorption reaction, the correlation coefficients were highly significant. The fitting results show that: the incubation time for 10d, 30d and 60d, soil NH4 maximum adsorption capacity (Xm) with increasing straw composite improved material was applied to the amount of increased training time for 90d, the soil of NH4 The maximum adsorption capacity (Xm) was applied to the amount of straw improved materials 5g/kg highest. Straw the composite modified material was applied to the amount of the same dose PAM period NH4 Xm performance% gt PAM0.99; PAM0 gt; PAM1.96% gt; PAM2.91%, that is, the low proportion of PAM added amount (0.99%) to improve the the soil NH4 adsorption capacity, increase the proportion of PAM NH4 adsorption capacity to dampen. Modified material was applied to the amount of soil incubation time for each soil NH4 of Xm varies improved material was applied to the amount of 2,5 g / kg soil Xm reduce with prolonged incubation time, improved The amount of material applied into 10g/kg soil Xm is the highest in the culture of 60d. Fitting the data show that in all soil culture 60d, when straw improved material usage 10g/kg, the PAM add the proportion of 0.99% of the treated soil NH4-Xm greatest increases, from CK's 243.90mg/kg improve to 1111.11mg/kg. The impact of of straw composite improved materials the soil NH4 adsorption binding capacity (K) with the maximum adsorption capacity of soil NH4 (Xm). That straw the composite improved materials applied amount containing a low proportion of PAM to improve the adsorption capacity of the soil NH4 effect the best, but not the soil NH4 adsorption strength enhancement, but weakened. It is worth noting that, 5g/kg amount is applied to each processing in culture section 30d, and the adsorption strength than CK increased significantly, and both large significantly higher than other soil treatment, to achieve a significant level of difference (p LT; 0.05). Straw composite improved materials (4) was applied to the sandy soil to increase the desorption of NH4-N. Improved material usage phase at the same time, the proportion of the PAM soil NH4-N desorption rate impact of the law is not strong, soil NH4 desorption rate improved material usage increases with straw and improve soil on that straw application of improved materials can improve the total amount of nitrogen adsorption, but it can not improve the the holding capability nitrogen. (5) soil column leaching test results improved sandy soil leaching filtrate NH4 - N and N03'-N concentration and the cumulative amount of leaching than CK significantly reduced, and with straw composite improved material usage improved. Shown that increasing the amount of straw composite improved materials can effectively inhibit their migration, inhibition of nitrogen leaching losses. Composite improved material usage Leachate NH4-N and N03'-N concentration and accumulated the minimum amount of leaching PAM ratio of 0.99%, indicating that the straw composite improved materials add this proportion PAM can effectively inhibit the NH4-N and N03 - N leaching losses. The study showed that the treatment works best when straw improved material usage 10g/kg PAM proportion of added 0.99%, the final cumulative leachate in NH4-N and N03-N leaching, respectively, compared with 28.26% reduction in CK 41.50%.

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