Study Of Tillage Methods On Soil Properties And Corn Yield In Latosolic Red Soil Of Southern China

Tillage is essential in the improvement of soil properties for crop growth.Soil tillage can significantly alter soil properties,as it’s among the most important factor affecting plant growth characteristics and crop yield.Appropriate use of tillage can enhance soil-related constraints,while inappropriate tillage may cause a range of unwanted processes such as ruin of soil structure,accelerated erosion,lessening of soil nutrient and the interruption of water and air movements.The aim of this research was to investigate the effect of different tillage methods on soil physical properties,chemical properties,and biological properties.The impact of tillage methods on corn growth parameters,yield parameters,and economic returns were also investigated.Experiments were conducted in 2016 and 2017.A cultivar of Zea mays,Yue Tian 26（85 days ripening time）,was used in conducting the experiments.The experiments included four treatments:（i）two passes of rotary tillage（2RT at 20 cm depth）;（ii）subsoiling（SS at 40cm depth）;（iii）two passes of rotary tillage+subsoiling（2RTSS at 20 cm+40 cm depth combined）;（iv）zero tillage（ZT）,in a randomized complete block design（RCBD）with three replications each.The soil bulk density,mass moisture content and soil penetration resistance of the tillage methods were tested,and the soil porosity was calculated.The results from the study showed that,tillage method significantly（p<0.05）affected soil bulk density,porosity,soil penetration resistance as well as gravimetric water content.SS-treatment recorded lowest soil bulk density(1.41 g cm^-3),soil penetration resistance（1.81 MPa）,soil gravimetric water content（21.12%）,but highest total porosity（47.36%）as compared to ZT,2RT,2RTSS at 0-40 cm soil depth.The use of SS created a favorable condition for soil bulk density to decrease compared to ZT.SS loosen the soil by breaking the subsurface of the soil,which decreased the soil bulk density and improved soil porosity,enhancing the ability of soil water storage and root penetration.The SS improved the soil porosity thereby increasing the soil gravimetric water content.Penetration resistance was improved under SS due to the breaking of the soil hardpan.The biplot analysis showed 95.43%experimental variance.Hence,it can be concluded that,SS-treatment could be adopted as a promising soil management practices for sustainable crop production.The soil pH,soil organic matter（SOM）,soil organic carbon（SOC）,available nitrogen（N）and phosphorus（P）,exchangeable potassium（K）,total nitrogen（N）,P,and K were tested.Results showed that,in comparing with SS,2RT and 2RTSS,the ZT had higher SOC(208.66mg kg^-1),SOM(22.07 g kg^-1),available N(118.28 mg kg^-1)and P(80.40 mg kg^-1),exchangeable K(12.83 g kg^-1),total N(1.45 g kg^-1),total P(0.84 g kg^-1),and total K(12.88g kg^-1)in the 0-40 cm soil depth.The highest level of pH（4.77）was recorded under SS in the 0-40cm soil depth.The biplot analysis showed 91.78%experimental variance.The ZT improved the other soil chemical properties,with the exception of pH which was improved under SS due to the loosen up of the soil for enhanced water and air movement.Therefore,although ZT improved the other chemical properties,SS could be adopted on acidic soil for higher productivity.Soil bacterial indicators were assessed and analyzed.Results showed that,ZT treatment recorded the highest levels of bacteria(1.27×10⁵ cfu g^-1 dry soil)and actinomycetes(1.95×10⁴ cfu g^-1 dry soil)in 0-40 cm soil depth,whilst SS treatment increased the fungal(1.19×10³ cfu g^-1 dry soil)count and also a higher concentration of soil enzymes[urease(266.08NH⁺-N mg kg^-1),catalase 1.45{0.1NKMO₄ m L kg^-1}and phosphatase(292.06 P₂O₅ mg kg^-1)]in 0-40 cm soil depth respectively.The principal component analysis showed 96.05%experimental variance.Overall,although ZT facilitated more bacteria and actinomycetes,soil with ZT had lower soil enzymatic activities,and fungal count compared to SS treatment.SS treatment is therefore considered suitable approach to improve soil health and productivity.The corn growth and yield were determined from each treatment.The results on the corn growth and yield parameters showed that,highest plant（21.36 cm）,ear height（68.65 cm）,ear length（194.30 mm）,ear weight（341.13 g）,number of rows per ear（17.17）and number of grains per row（41.56）were observed under SS.Also,maximum grain yield 7.37 t ha^-1（9.81%）,dry matter(19.21 t ha^-1),harvest index（38.36%）and 1000-grain weight(299.88 t ha^-1)were recorded under SS.The principal component analysis showed 87.88%experimental variance.SS facilitated highest corn yield and yield components and therefore could be adopted as a strategy for higher productivity leading to a sustainable agricultural system under the changing climatic conditions.Corn productivity output was evaluated to determine the economic returns of each tillage method.The results showed that,ZT resulted in higher net benefits(11,251.42￥ha^-1)compared to SS 11,062.98￥ha^-1,2RT 10,580.93￥ha^-1,and 2RTSS 10,237.12￥ha^-1.Although,SS treatment resulted in higher yield,the profit return was less compared to ZT due to the fuel consumption rate of the treatment application.Maximum marginal rate of return was obtained under 2RTSS（644.16%）compared to 605.57%and 188.44%under2RT and SS respectively.Although,ZT obtained the highest net benefit,SS could be exploited more in improving soil health and quality.Results from the study showed that SS leads to enhancement in soil health and quality in the soil（0-40 cm）,and results in sustainable increase in corn grain yield.In general conclusion,SS could be adopted as a promising approach for soil management practices and higher corn productivity leading to a sustainable agricultural system to feed the growing population.