【作者】 褚清河；

【导师】 潘根兴；

【作者基本信息】 南京农业大学 ， 土壤学， 2008， 博士

【副题名】以北方旱作系统为例

【摘要】 我国粮食生产经历了依靠品种更新和肥料施用而到达高产的发展阶段。当前的高产农业基本上以高肥料投入为代价。但这带来了肥料利用率不断下降,养分资源流失而加剧农业非点源污染。因此,配方施肥和精确施肥成为我国农业养分利用与施肥技术发展的方向。对于北方旱地农业,已经有许多关于合理施肥促进旱作物高产高效的研究。本文主要以山西旱地土壤-作物系统为对象,从传统的最小因子理论为基本依据和出发点,通过改进施肥试验的设计方法,同时考虑养分供应量与供应比例,在不同地区和不同土壤上设计和实施了玉米、小麦和烟草(部分)的多点田间实验,研究了土壤养分供应状况与氮磷施肥比例、施肥量与产量的函数关系、最大施肥量与边际产量的依变关系,并探讨了旱地作物对土壤养分的吸收利用特点及其与旱作物营养遗传特性的关系,得到如下结果:1、在所研究的区域和土壤类型上,土壤养分供应状况可以分为养分平衡供应与不平衡供应状况,特别是在贫瘠土壤或养分损耗下这些状况尤其明显。因此,在旱地土壤不同养分供应状况下,玉米、小麦及烟草等旱作物的施肥不但需要解决氮、磷、钾养分的最佳供应量,而且需要考虑其最佳施肥比例。施肥比例的作用在于调整土壤养分供应由不平衡供应转化为平衡供应或保持土壤养分供应的均衡性,使作物能高效利用所供应的养分,而施肥量则主要是满足作物苗期所要求的土壤供肥强度。试验表明,氮、磷施肥比例显著影响玉米对氮、磷养分的吸收及秸秆中氮素的积累和利用。在最佳氮、磷施肥比试验下,不同处理玉米的氮素利用率在44.8%～48.2%之间,每kg氮素的玉米产量贡献率为38.9～41.4kg;而以磷定氮试验下,玉米对氮素的利用率随施氮量增加而降低。在氮磷施用比例合理条件下,施肥量小于最大施肥量则很少发生肥料氮磷养分的土壤积累,而施肥量大于最大施肥量时则有利于土壤有机质的积累和N、P养分的土壤保持。氮、磷施用比例不协调或氮肥过量施用,则减少玉米对土壤氮、磷的吸收,形成磷肥在土壤中的积累,从而降低磷肥利用率。2、以磷定氮与氮、磷等比例两种试验方案下试验得到的玉米最大施氮量存在一定差异,且明显受试验氮、磷设计比例的影响,其产量效应可以用不同的函数方程描述。在实际施肥量小于最大施肥量下,玉米边际产量随施肥量的变化较小,且以氮、磷最佳比例下为最高,但施肥量大于最大施肥量时则显著降低。产量效应的数学模拟表明,作物产量与施肥量的关系可以用带有极点的两条相交直线来表征,以此求得的作物最高产量施肥量更好地反映了边际产量与施肥量的依变关系,因而可能更符合田间实际施肥需要。看来,作物最高产量施肥量主要是由土壤肥力水平和土壤中不同养分的配比关系决定的,并不受气象因素的制约,但气象状况显著影响最大施肥量的农学效率。3、对参加北方玉米区试的一系列玉米品种进行了平衡与不平衡的对比施肥试验,表明不同玉米品种因其营养遗传特性不同而影响其对养分的利用能力与产量潜力:1)一些在土壤养分供应不平衡条件下区试增产不明显的品种,改在平衡供应条件下种植则可能有高产潜力;2)能适应土壤养分平衡与不平衡供应种植的品种,在不平衡供应条件下种植的增产效果更明显;3)在不平衡土壤养分类型上表现出较大增产潜力的品种,在养分平衡供应条件下增产效果可能很有限。品种选育中施肥是否合理,在很大程度上影响所选育品种的产量潜能,并可能影响所形成的品系或区系材料的产量遗传稳定性。根据土壤养分供应类型选择种植相应的品种,是土壤养分有效利用的一个新途径。本文的研究试图说明,在传统土壤-植物营养研究上,田间试验仍是获得肥料与作物产量关系的主要途径,但是作物产量与施肥量的关系可能不是简单的抛物线关系,考虑施肥量和施肥养分的不同配比关系,这种关系可以用养分边际效应递增和递降的不同曲线的交切来理解。这对高产施肥量的合理选择是很重要的。更多还原

【Abstract】 Cereals production in China has experienced several stages of development due to cultivar innovation and fertilizer application.High input of chemical fertilizers has been overspread in China for high yielding since 1990’s.However,high rates of of fertilizer application may have resulted in decreasing use efficiency and increasing runoff loss as a source of non-point source pollution from farmplands.Therefore,formulated or precise fertilization had been a new frontier for nutrition and fertilization technology development in agriculture.There had been numerous studies on the rational fertilization for dry croplands of North China since 1990’s.This dissertation deals with rational fertilization with dry crops by field experiments concerned with both the pool and proportion of nutrients in supply,taking examples of corn and wheat production in drycropland soils from Shanxi province,China.The fertilization schemes were developed from the hypothesis of "minimum nutrient control’ and with improved design concerning both the nutrient supply rate and proportion.The experiments had been conducted in a series of soils from different locations and crops of tobacco,corn,and wheat with different nutrient demands.The response of crop yield to different fertilization schemes were studied for deducing the best total fertilization rate and proper proportion for high yielding production.In addition, uptake and utilization of soil nutrients by different types of crops and the effect of the phyllogenetic nature of crop culticvars were also discussed.The main results were as follows:1,The status of soil nutrient supply could be divided into two main types of balancing and non-balancing supply of the soils studied.This was especially true when soil nutrient pool was exausted under continuous cultivation.Therefore,dry crops should be supplied not only a rational total amount of fertilizsers but a proper proportion of the nutrients applied with N,P and others when seeking high yielding producitivity of corn,wheat and tobacco as well.In this means,fertilization is aimed to adjust the supply rate of soil in an enough amount to meet the crop requirements so that crop could use efficiently for a potentially high yield.Whereas,the fertilization rate is only to meet the requirement at the seedling stage for the potential growth for biomass buid-up.The proportion of nutrient supply affects not only the total uptake of crops but the maximum yield.The use efficientcy of nutrient fertilized could be increased under a proper ratio of N to P as a high N use efficiency of 44.8%～48.2%was observed under balanced fertilization for corn and a contribution to grain yield of per kg of N turned to be as high as 38.9～41.4kg.Inproper N to P ratio could result in reduced nutrient uptake by corn and accumulation of excess of P in soil after harvest,thus reducing P use efficiency;2,Difference in the maximum fertilization rates for corn was observed between using N application rate following P rate and using consistent proportion of N to P in fertilizer application.The maximum application rate of N and P for highest yield depends on the ratio of N to P.The marginal yield response could be described with different type of regression functions.The marginal yield response seemed small variation with application rates under a fertilization rate loewer than the maximum rate.However,the marginal response turned smaller when the application rates in excess of the maximum rates.The response to nutrient supply rates could be staitisatically modeled with two linear curves with the corss point at the maximum fertilization rate,which may reflect the actual marginal effect of supplied nutrients in a proper proportion.It is concerned as a real demand of nutrient for high yielding production in the field.It is likely that the maximum fertilization rates were determined by soil fertility and the nutrient proportion in supply of the soils under cultivation.Nevetheless,meterological conditions may have effects on the agronomicial efficient of the supplied soil nutrients.3,An experiment with a series of new cultivars in a regional test was also conducted with the balabcing fertilization schemes,demonstrating a potential control of phylogenetic properties on the nutrient uptake and the marginal yield response.High potential yield may be obtained of some cultivars breeded under imbalanced soil nutrient supply when grown under balanced supply of fertilizer nutrients;Whereas,some cultivars adapting to both balancing and imbalancing soil nutrients may have higher yield potential when grown under imbalanced soil nutrient status;However,limited yield increase would be expected when grown under balanced soil nutrient status of some cultivars breeded under imbalanced status.The yield potential seemed to be controlled in a great deal by the soil nutrient supply when they were breeded,which may in turn affect the genetic stability of the productivity of the cultivars under breeding.Therefore,a new approach for cultivars breeding by adjusting soil nutrient supply status could be developed.This study may offer a new insight into the actual yield response curve when using nutrient supply rate and proportion in field experiments of fertilization schemes in classical soil-plant nutrition study.It is suggested that the marginal response would be characterized by a decreasing yield unless an improper ration of N to P be applied.The response curve may be interpreted with a cross point of a maximum yield of two linear response curve both an increasing and a decreasing trend turning at the maximum rate,which reflect the different marginal yield response depending on the rational maximum rate and the balancing status.This offers a scientific base for recommending a high yielding and high use effiency fertilization shceme for dry croplands of North China.更多还原