Study On The Effect Of Biomass Ash On Repairing Degraded Soil

Currently, soil and land degradation due to a variety of irrational human activities, has been a serious threat to the sustainability of agriculture worldwide. Degraded soil conditioner is a new method developed on the basis of modern industry. However, the effects of different ameliorant were different, due to thire the structure and properties, mechanism and so on. Therefore, seeking a new, cheap and environmental modifier is an issue that the majority of agricultural scholars of common concern about.Biomass Ash is the combustion products of agricultural waste. It is an alkaline, with a porous structure, not only can improve soil physical and chemical properties, but also can promote the growth of crops, reducing the incidence of disease, creating a favorable soil environment. It is a renewable type of green energy, favored by many scholars.In this paper, Chongqing typical purple soil and yellow soil are studied.This paper thoroughly studied the effect of different ash content on the improvement of the purple soil and yellow soil through a pot experiment and a field experiment in order to choose a proper ash content. Besides, this paper further analyzes the effect of different modifier on the improvement of the yellow soil through a pot experiment in order to choose a proper modifier. The ash content and modififer provide a scientific basis in the application of the agricultural sector, and develop reasonable measures for the restoration of degraded soils, realizing the goal of recycling and sustainable agriculture.The main conclusions were as follows:(1) In the pot pre-culture experiments, the influences of ash on the degredated yellow soil and the quality of vegetables were significantly different. Ash in high can effectively improve the physical and chemical properties、crop qualities, especially the ash in the proportive 5% and then the ash in the proportive 5% would be chosed to the further comparative study of different modifiers on the improvment of degraded soils(2)The effectives of different ameliorants on the crop productives and qualities were different.The the amounts of vegetable productions in the treatment NPKH and NPKW were lager than others. Compared with CK, the lettuce NO3--N contents in other treatments were higher. The NO3--N contents met the GB/T15401 requirements, so they did not be harmful to the nature of plants. Chemical fertilizer with ameliorants helped reduce more lettuce NO3--N contents than Chemical fertilizer singly, the treatment NPKW being best, the treatment NPKSF being better. The soluble reducing sugar contents in NPKS and NPKW were higher than others, while the amino acid contents in NPKH were higher than others.(3) The effectives of different ameliorants on the degredated soil were different. The degraded soil organic contents under the modifiers increased, with increased planting time soil organic contents decreased, but the decline of organic contents in NPKH was least, followed by the NPKC. The soil pH was increased under the modifiers. In the same season, the soil pH showed NPKH>NPKSF>NPKS>NPKW> NPKC>CK> NPK. Chemical fertilizer with ameliorants helped increased more soil TP and TK contents than chemical fertilizer singly, especially the contents in the treatment NPKH> NPKW and NPKC. The soil available N was not significant, while the soil available P and available K were very significant, especially the soil available P in the treatment NPKH increased by 190.0%～242.9%.(4) The effectives of different ameliorants on nitrogen and phosphorus in soil infiltration were different. The chemical fertilizer single on degraded soil could easily lead to the loss of nitrogen (TN loss of concentration 22.08-39.06 mg/L). The nitrogen concentrations of the water infiltration in the treatment NPKH、NPKW、NPKC were lower than others. The NO3--N concentration was the main form of soil nitrogen losses, similar trends with TN. There was a significant correlation between the NO3--N concentration and TN(p<0.01, r=0.869)in the water infiltration. The NH4+-N concentrations were low and controlled in 1 mg/L or less. In the pot process, the TP and DP concentration in the water infiltration had a similar trend, there was a significant correlation(p<0.01, r=0.892). The DP concentration accounted for more than 60% TP. The TP and DP concentration of the water infiltration in the treatment NPKH were 0.70～1.35 mg/L and 0.67～1.27 mg/L, significantly higher than other treatments’. Ash itself contains a lot of phosphorus, except for crop growth, the part will be lost with the water, so the phosphorus of of the water infiltration in the treatment NPKH were more than others that could easily lead to eutrophication.(5)Based on Savigny’s method and Le Bissonnais method, the effectives of different ameliorants on the soil aggregate water stability and distribution characteristics were different. Compared with the control CK, the soil>0.25 mm air-dried aggregates contents in the treatment NPKW and NPKC increased, the soil>0.25 mm aggregate water stability in the treatment NPKH was high and the damage rate of soil aggregates was lower than others. The fractal dimension D in the treatment NPKH was lower than others. Through the analysis of soil aggregates crushing mechanism, it showed that the soil<0.25 mm aggregates contents in the treatment NPKH increased by 6% to 10% after the LB, especially the soil<0.25 mm aggregates contents after WS way was least, only 3.75%. Even under strong disintegration FW way, the lager aggregates in the treatment NPKH was more. In a word, the treatment NPKH can improve oil aggregate stability, followed NPKW treatment. The soil MWD and GMD in the treatment NPKH were more than others, it can maintain high stability when coming across raindrops, farmings or other endures stresses, followed by the treament NPKSF and NPKW. Howere, compared to other treaments, the soil in the treatment NPKH was easily broken by the air squeeze. Therefore, when the soil was added ash, etc., should pay more attention to the effective protection of soil slope on the storm season, enhanced the soil slope erosion resistance and stability.(6)The soil macrofunction is directly reflect the mechanical properties of the soil, and is closely related to the intensity and soil erosion, landslides and so on. In the pot experiment, the soil WP in the treatment NPKH was increased and others were decreased. After planting spinach demanding greater water the soil WL in the treatment NPKSF、NPKH、NPKW、NPKC were decreased. The soil IP in the treatment NPKH was decreased and others were increased. After rotation, the soil IL increased, especially the treatment NPKH, followed by NPKW.(7)In the field test condition, the vegetable productions and the qualities of degraded soil under the different amouts of ash were different. Compared with the control, the vegetable productions increased with increasing application rates. The highest yield 1200 kg/acre treatment was higher by 443.20～662.20 kg/acre than the control CK. Applying a large amount of ash can improve soil organic matter content. Ash is alkaline, the soil pH under the ash handling were improved. In a short time, the application of a large number (1000-1200kg/acre) of ash can quickly reduce soil exchangeable Al3+content, improve soil pH, and the effect was obvious. In addition, the application of ash can effectively improve soil P, K contents. While the improvement effect has declined with planting time and the high ash fertilizer (1000～1200kg/acre) processing is still higher than other treatments.(8) In the field test condition, the soil aggregates particle size distribution is low in the middle on both sides of the high trend in wet sieving measured and the soil<0.25 mm diameter aggregates content was above 40%. In the early application of ash, ash on the soil great aggregate water stability had a better effect, and the more amounts of ash, the more effective there would be. With the planting time, the soil great aggregate water stability were increased, while the micro-aggregates were decreased, In a word, adding a large of ash can increase the soil aggregate stability in a short time, and ash the greater the amount of slag applied, the better the results.(9) In the field test condition, ash can reduse the soil from the "bacterial-type" to "fungus-type" level even as obstacles. With the planting time, the effect of high levels of ash handling treated better than others. The amount of ash increased the SMBC obviously. The SMBN increased early in the trial, and it would be more in the high levels of ash with the planting time.