Study On Nutrient Utilization And Soil Effect Of Summer Maize Under The Different Tillage Methods

In the Huang-Huai-Hai area,several problems exist such as the soil plough layer is shallow,the plough bottom layer is thickened year by year,and the plant roots are difficult to grow deep due to long-term fertilization to upper soil profile and no-tillage cultivation.Besides,the application of all fertilizers at sowing without top-dressing caused premature senility of maize resulted from not enough nutrient supply at late growth stages.Therefore,field experiments were conducted to investigate the effects of different tillage and fertilization methods on plant growth,nutrient uptake and utilization,and yield of maize as well as economic benefit,soil physical characters and temporal-spatial distribution of soil nutrients in maize production under wheat-maize rotation system.Nine treatments were designed and conducted as follows:no-tillage+upper NPK;no-tillage+upper PK;no-tillage+upper NK;no-tillage+upper NP;subsoiling+whole layer NPK;subsoiling+whole layer PK;subsoiling+whole layer NK;subsoiling+whole layer NP;and application of N,P,K fertilizers to designated different soil depth with subsoiling.The main conclusions were:?1?The combined application of NPK fertilizers increased plant height,ear height,SPAD value of ear leaf,ear length,grain number per spike,100-seed weight and yield of maize comparing to fertilizations without N-,P-or K-containing fertilizers.Among treatments with combined application of NPK fertilizers,the dry matter accumulation and yield of maize as well as grain yield of the following wheat were all showed the same trend as fertilization to designated different soil depth with subsoiling>subsoiling+whole layer fertilization>no-tillage+upper layer fertilization.Specifically,the dry matter accumulation of maize at harvest,maize yield and the following wheat grain yield in treatment of fertilization to designated different soil depth with subsoiling were 10.75%and 16.49%higher,9.55%and 22.41%higher,and 2.68%and 7.47%higher than those of subsoiling+whole layer fertilization and no-tillage+upper layer fertilization treatments,respectively.?2?In terms of plant nutrients accumulation,the plant N,P,K accumulations at maturity showed similar trend to that of grain yield,being fertilization to designated different soil depth with subsoiling>subsoiling+whole layer fertilization>no-tillage+upper layer fertilization.Compared with subsoiling+whole layer fertilization and no-tillage+upper layer fertilization treatments,N,P,K accumulations were enhanced by10.35%,11.87%,7.94%and 23.02%,20.87%,26.57%,respectively.These results indicated that the subsoiling practice could increase the plant nutrients accumulation.Besides,the effect was more sound with the combined application of NPK fertilizers.?3?Both types of subsoiling treatments could effectively increase the apparent utilization of nutrients,production efficiency,agronomic efficiency and economic benefit in maize.The utilization efficiencies of N,P,K fertilizers were highest in treatment with fertilization to designated different soil depth with subsoiling,reaching 56.7%,47.6%and59.7%,respectively.The net income from subsoiling+whole layer fertilization and fertilization to designated different soil depth with subsoiling treatments were increases by1880 yuan/hm² and 3843 yuan/hm² over that of no-tillage+upper layer fertilization treatments,respectively.Therefore,the fertilization to designated different soil depth with subsoiling method had superior economic benefit in maize production.?4?Compared with no-tillage+upper NPK treatments,the soil bulk density was decreased by 5.52%,the compactness pressure value was decreased by 20.27%,the soil water content was increased by 6.63%,the soil moisture infiltration rate was increased by55.1%averaged from subsoiling treatments.However,no significant differences were found between these two types of subsoiling treatments in the present study.These results implied that the plant root growth may be enhanced due to the improved soil physical characters by subsoiling.Moreover,in terms of soil nutrient contents,the treatment of application of N,P,K fertilizers to designated different soil depth with subsoiling increased NO₃^--N,NH₄⁺-N,available P and available K contents in 20-40 cm soil profile at maize stem elongation stage by 13.87,3.97,10.64 and 35.55 mg/kg compared with those in no-tillage+upper NPK treatment,respectively,and by 2.02,0.69,5.70 and 22.68 mg/kg than those of subsoiling+whole layer NPK treatment,respectively.These results implied that the treatment of application of N,P,K fertilizers to designated different soil depth with subsoiling might provide more nutrients to meet the nutrients demand of maize at late growth stages.Based on results from the present study,it could be demonstrated that the subsoiling practice could effectively alleviate the problems of thickening of the soil plough bottom layer and low fertilizer utilization efficiency caused by long-term no-tillage practice.Besides,the subsoiling practice could reduce soil bulk density and hardness,improve soil water retention performance,and promote the growth and development of maize roots.The practice of application fertilizers to designated different soil depth with subsoiling could effectively supplement nutrients in the 20-40 cm soil layer,increase the fertilizer utilization efficiency,as well as increase yield and economic benefit of maize and the following wheat.Therefore,it might be a new cultivation and fertilization technology which is worth being demonstrated and extended.