Influence Of Reducing Chemical Fertilizer On Cotton Growth And Nutrient Losses

Cotton growing period is very long,much water is needed,to meet production needs,cotton fertilizer of China's Yangtze River valley in the production is continuing to increase,but the cotton yield did not rise,and increase the environmental burden.This article is based on cotton growth characteristics,combined with the feature of regional characteristics and rainfall of Jianghan plain,using field experiment,setting up a series of fertilization scheme,aims to put forward a set of economize manure fertilization technology,and provide a reference basis in Jianghan plain area about the control of agricultural non-point source pollution at the same time.In order to research the relationship between the fertilization and cotton biomass,yield of cotton,the nutrient uptake and utilization rate of fertilizer,the field experiment was made that is a decrement experiment of different chemical fertilizers.In the field experiment,chemical fertilizer used by local farmers was as the contrast?CK?,another seven fertilization sets is:80%-N biological organic compound fertilizer?T1?,80%-N controlled release processing mixed fertilizer?T2?,80%-N organic inorganic fertilizer treatment?T3?,80%-N biological organic compound fertilizer N treatment?T4?,80%-K organic inorganic fertilizer K treatment?T5?,no potassium treatment?T6?and no nitrogen treatment?T7?.In addition,chemical fertilizer decrement experiment was conducted in blooming and boll-forming stages so as to explore nutrient loss from runoff under fertilizer decrement and to formulate better measures for cotton nutrient management in rainy season,in which the local conventional fertilizer amount was as contrast?CK?,and two fertilization treatments,one using 80%of CK?T1?and the other using 60%of CK?T2?.The following basic conclusions can be obtained through analyzing field experimental results from fertilizer decrement experiments that are:Firstly,compared with CK,the dry matter weight of cotton under different fertilizer treatments variation is-0.38%,20.49%,9.27%,-0.47%,7.63%,-35.49%,-41.07%,T2and T3 cotton dry matter weight can be increased,T2 and CK reached significant difference levels;The order of seed cotton is T2>CK>T1>T3>T5>T4>T6>T7,T2 cotton yield is the highest,2936.5 kg/hm²,no nitrogen treatment?T7?yield is the lowest of 1727 kg/hm²,compared with the conventional farmers fertilizer?CK?,the rest of the cotton production variation is:-1.10%,3.37%,-1.44%,-4.64%,-5.60%,-39.20%,-34.72%,T2,T4,T5,T6,T7 has reached significant differences level with the CK;There is no significant differences between the groups of fiber yield.Secondly,at cotton boll opening stage,the different treatments of nitrogen uptake is 1.21⁴.81g/strain,T7 is the lowest and T5 is the highest.Compared with CK,the other fertilizer processing cotton nitrogen uptake variation is:0.94%,3.51%,2.29%,1.37%,12.88%,-34.55%,-71.53%,T5 has biggest amount of increase and reached significant difference level.T6,T7 has dropped significantly,and reached significant difference level.Potassium absorbed by cotton under different fertilizer treatments is1.29³.06g/kg,compared with CK,other fertilizer processing cotton potassium uptake variation is:-0.47%,27.42%,3.61%,-15.65%,-6.21%,-75.64%,-46.31%,potassium uptake has a significant reduction because of potassium fertilizer reduced,no potash can be maximum,and reached significant difference levels.Thirdly,under the conventional fertilization treatment,the nitrogen uptake,nitrogen apparent utilization efficiency,nitrogen partial productivity and agriculture utilization are 4.27 g/strain,18.09%,9.71 kg/kg,3.81 kg/kg.Under the reducing nitrogen fertilization treatment,the nitrogen uptake,nitrogen apparent utilization efficiency,nitrogen partial productivity and agriculture utilization of T1,T2 and T3 is increased,and the effect of T2 is most obvious,they are 4.42g/strain,22.43%,11.86kg/kg,4.89 kg/kg,and the nitrogen apparent utilization efficiency,nitrogen partial productivity and agriculture utilization reached significant difference levels compared with CK.Under the conventional fertilization treatment,the potassium uptake,potassium apparent utilization efficiency,potassium partial productivity and agriculture utilization are 2.40 g/strain,16.13%,14.57 kg/kg,5.06 kg/kg.Under the reducing potassium fertilization treatment,the potassium uptake of cotton is reduced,drops of15.65%,6.21%and 75.64%respectively,and with T6 is most obvious.The potassium apparent utilization efficiency,potassium partial productivity and agriculture utilization of T5were significantly higher than CK,they are 18.19%,17.66 kg/kg,5.77 kg/kg,and potash partial productivity has reached significant level.Fourthly,after cotton receiving,the topsoil of alkaline hydrolysis nitrogen content of CK is 91.25 mg/kg,compared with CK,the topsoil of alkaline hydrolysis nitrogen content of T1,T2 and T3 increased by 2.57%,8.58%and 4.65%,and T2 shows significant difference.The topsoil of available potassium content is 139.95 mg/kg,and the content of T4 and T5 decreased by 10.99%,4.00%,but still can not reach significant difference levels.T6 is decreased by 49.00%,reached significant difference levels with CK.By analysis of experimental results obtained by fertilizer decrement experiment which was conducted in blooming and boll-forming stages of cotton,the following preliminary conclusions can be made:Firstly,compared with the CK,T1 and T2 significantly reduced the average concentration of total nitrogen?TN?,NH₄⁺,NO₃^—,total P,DP and DRP in the sur-face runoff after heavy rainfalls.The decrease in TN and TP was 2.50 and 0.183 mg/L respectively under T1,and3.41 and 0.234 mg/L respectively under T2.Secondly,the yield under CK,T1 and T2 was 3500,3364 and 3242 kg/hm²,respectively.The yield in T1 and CK was comparable,but there was a yield loss in T2.Therefore,reducing fertilization at the blooming and the boll-forming stages by 20%?505kg/hm²?from the conventional fertilization could alleviate nitrogen loss from the surface runoff without scarifying yield.