Study On Soil Environmental Benefits And The Application Effect Of Biodegradable Polymeric Slow/Controlled Release Fertilizer

Slow/controlled release fertilizer is significant in increasing crop yields, reducing quality resource waste and environmental pollution due to high nutrient utilization, and its application and development gets the focus of world attention. As a novel chemical-type slow/controlled release fertilizer, biodegradable polymeric slow/controlled release fertilizer is rich in nutritional elements and is biodegradable by microorganism in the soil, which has the advantage compared with urea formaldehyde fertilizer and coated slow/controlled release fertilizer. In the current study, the biodegradable polymeric slow/controlled release fertilizers produced by Research Center for Engineering Technology of Polymeric Composites of Shanxi Province were choosed as the experiment materials. Firstly, the method for determination of the formaldehyde of fertiliaer and the impact on soil during the the period of application or degradation was studied. And the tomato pot experiments and corn field experiments were investigated to study the effect of the different biodegradable polymeric slow/controlled release fertilizers on the crops. Specific results are as follows:(1) A simple and accurate method for the determination of residual formaldehyde in biodegradable polymeric slow/controlled release fertilizers has been established. The method was based on the reaction between formaldehyde and fluoral P and then determined by the UV-VIS spectrophotometer simultaneously at 413 nm. Under the optimized experimental conditions, the method allowed the determination of formaldehyde in the range of 0.2–4.0 ug mL-1 with good precision, and the limit of detection was measured as 0.02 ugmL-1. The relative standard deviations for the determination of 0.1 and 0.3 ug mL-1 of formaldehyde ofsample were 3.5% and 2.0%(n=5) respectively, and the recovery ranged from 96.5–105.5%.The proposed method was proved to be an accuracy and precise method with good reproducibility.(2) Dynamic variation of formaldehyde of biodegradable polymeric slow/controlled release fertilizer and commercially urea formaldehyde slow release fertilizer in the soil was studied under the condition of different temperature and soil water content. Experimental results suggested that formaldehyde content showed a trend of fluctuations on the whole, and the maximum ormaldehyde content in soil was less than 0.3 mg/g, therefore there was little or no impact on the soil environment. The addition of root secretion made less formaldehyde content and changed in the parochial bound. Urea formaldehyde fertilizer also presented the state of fluctuating, and the maximum content appeared earlier and higher than biodegradable polymeric slow/controlled release fertilizer, because nutrient release rate was faster and release longevity was shorter.(3) Different fertilizer treatments had remarkable effects on improving tomato leaf chlorophyll content and nitrate reductase activity, enhancing the root absorption ability,improve tomoto quality and increasing its yield. Among them, the biodegradable organic polymer slow/controlled release NPK fertilizer(PRF) and micronutrient fertilizer(WRF)were superior to Tomato fertilizer(CCF),and even organic-inorganic compound fertilizer(OM +INF), but the effect of sulfur fertilizer was lower than CCF and OM +INF. Moreover,low-solubility fertilizer could meet the demand of the tomato growth better. PRFL improved tomoto yield by 75.39%, nitrate reductase activity and root activity was more than CK 2.2and 17.8 times, respectively. And the test results showed the tomoto treated with PRFL is great taste and fruit quality was better than other’s. In addition to the WRF, catalase activity of other treatment were higher than CK and the difference was not significant, this illustratedthe catalase activitie was almost not influenced by the fertilization treatments. Soil urease activities with different fertilization were higher than CK except WRF, and biodegradable polymeric slow/controlled release fertilizers still were able to release a certain amount of nutrients in tomato maturation, of which urease activity treated with PRFL was beneficial to improving soil fertility was 1.2 times that of CK treatment. Low soil catalase and urease activities treated with WRF could be related to inhibitory effect of Fe、Mn、Cu、Zn of WRF.(4) PRF treatment had the highest chlorophyll content that increased by 20.1%compared to CK treatment in the maize jointing stage. At the huge bellbottom period,chlorophyll content treated with PRF and WRF was higher than other treatments, which was much more 16.0 % and 14.9% than CK, respectivily. Furthermore, biodegradable polymeric slow/controlled release fertilizers were of great effect in improving content of soluble sugar,starch, protein, and fatty acid value showed that its storage quality was very good. Soil catalase activity of other fertilization treatments was higher than CK but different treatment has little or no effect on the catalase activity. Soil urease activities with different fertilization were higher than CK except WRF, and PRF had the highest urease activity was 2.1 times of CK treatment in the corn maturity stage. Besides that, biodegradable polymeric slow/controlled release fertilizers could increase corn production at different levels, among them,PRF had improved the most, increased by 17.8% compared with CK.