Land Equivalent Ratio of Groundnut-Fingermillet Intercrops as Affected by Plant Combination Ratio,and Nitrogen and Water Availability

Abstract

Field experiments were conducted to characterize intercropping advantages in groundnut-fingermillet intercrop in relation to crop combination ratios, soil moisture and nitrogen (N) availability. Three intercrops in 1 : 2, 1 : 1 and 2 : 1 alternating rows of groundnut and fingermillet were examined for their growth and yield in comparison with their respective sole crops in 1996. The effect of well watered (W) and water stressed (D) conditions on the intercropping advantage was also examined for 1 : 1 intercrops in 1995 and 1996. Fertilizer N was applied at the rate of 20 kg ha^?1 in 1995 and 50 kg ha^?1 in 1996. The total above-ground biomass (DM) and its land equivalent ratio (LER) were highest in the 1 : 1 combination ratio. The DM production of intercropped fingermillet was higher in 1996 with higher N than in 1995 with low N application, while those of groundnut were similar in both years. The intercropped groundnut exhibited significantly higher DM production after the fingermillet harvest. The LERs in grain yield were higher in 1996 (1.43 under W and 1.45 under D), than in 1995 (0.87 under W and 1.22 under D). Also, LERs were consistently higher under D than W conditions. Water stress severely reduced the leaf area index (LAI) of fingermillet at a low N, especially in the later stages, whereas higher N alleviated the water stress effect. A close linear relationship was observed between LAI and leaf area (LA) per unit leaf N both for groundnut and fingermillet, with intercrops producing larger LA per unit leaf N than sole crops. Intercropping maintained higher ability in leaf net photosynthesis and transpiration of groundnut up to later stages, and significantly reduced water evaporation from the soil surface under the canopy than sole cropping of fingermillet. These results suggest that three processes associated with the intercropping yield advantages in the groundnut-fingermillet intercrop; 1) higher leaf photosynthesis and vigorous growth of groundnut after the fingermillet harvest, 2) higher LA production per unit N and 3) efficient water use. In conclusion, interspecific shading was considered to be the key mechanism associated with these processes, leading to the intercropping advantages. The degree of the interspecific shade and its effect on growth and yield depended on the available soil N and water.     

我国征地补偿制度的研究

目前的征地活动在理论和具体的实施过程中还存在着一些不具体、不合理的地方。为了促使征地过程顺利进行,维护被征地人的合法权益,实现社会的可持续发展,一方面要努力提高征地补偿标准;另一方面在实践过程中要努力使补偿方式多元化、长期化。     

陕南贫困山区农村土地流转特点和存在问题及对策——以安康市为例

党的十七届三中全会后,陕南贫困山区的土地流转呈现出政府主导、政策激励的局面,在分析贫困山区土地流转特点的基础上,指出了土地流转中存在的问题,提出了推进贫困山区土地流转的对策建议。     

基于ERT技术反演红壤剖面水分入渗过程

水分运动是土壤中物质和能量传输的主要驱动力，但是水分在土壤中的运动轨迹复杂多变，难以直接捕捉。本研究以第四纪红黏土发育的红壤为研究对象，借助电阻率成像技术（ERT），反演水分在林地和农地土壤中的入渗过程。研究发现，ERT技术能够实现水分在红壤包气带入渗过程的可视化，ERT测定的表观电阻率的变化量与烘干法测定的土壤水分之间呈极显著正相关关系（P<0.01），林地的决定系数为0.72，农地为0.53。土地利用类型影响水分入渗的范围和方式，在2 cm水头高度注水100 L的情况下，林地的入渗深度大于80 cm，而农地约为50 cm，在此基础上，继续注水200 min，林地和农地均出现明显的优先流现象。但是，林地的优先流比农地更为发育，林地是通过根系等大孔隙快速向下传输，而农地则以“指流”的方式，间断性向深层运动。在土壤层次复杂、背景含水量高、土壤黏重等不利因素的影响下，ERT技术依然能捕捉优先流在红壤中发生和发育的过程。     

孙中山土地利用思想探讨

在介绍孙中山土地利用思想产生的原因的基础上,探讨了其思想的发展历程,指出了其思想的特色以及对人们的启迪。     

对土地利用基本特性的新认识

建国以来，一切在计划经济的原则下，片面强调了土地作为资源——生产资料的一方面，而忽略了经济特性的一方面。随着市场经济的发展，必须强调土地的自然和经济的双重性。本文用动态的观点，从土地利用的各个方面论述了土地在利用过程中表现出来的主要特性，较为全面地继承和发展了土地利用特性的认识观，提出了：土地地理位置的固定性与相对位置的可变性的相对统一、土地利用的永续性与土地利用的可退化性的相对统一、土地物质投入产出报酬的递减性与科技投入产出报酬的递增性的相对统一以及土地利用适应市场价格变动的缓慢性等六个土地利用的基本特性。我们认为，这一观点将对我国土地利用管理理论和制度的发展产生积极作用。     

连云港市区土地级别调整的实践性研究

从连云港市最近几年土地利用的实际发展情况和要求出发,探讨了其城市土地级别体系调整的必要性和合理性,以及技术路线和技术方法,建立了连云港市新的土地级别体系。     

马克思关于农业发展两条道路的思想

马克思的农业发展理论实际上经历了前后两个阶段的变化。早期,马克思强调西欧,特别是英国的经验,将农奴制下的农村公社—自耕小农土地所有制—资本主义雇佣型大农业—社会主义集体合作制大农业的发展序列作为人类社会农业发展的唯一道路。晚年,马克思的农业发展理论发生了转变,特别是对农村公社,以及自耕小农土地所有制和资本主义大农业的发展问题产生了新的认识。他认为农村公社包含了公有与私有两重因素,因而,农业发展道路并不是唯一的,完全有可能通过公有因素战胜私有因素使农村公社直接过渡到社会主义集体合作制大农业,而不必经过自耕小农土地所有制和资本主义大土地所有制的发展阶段。     

阿拉善左旗土地合理利用的途径

本文分析了阿拉善左旗资源与环境,论述了土地利用现状及存在的问题,并提出在荒漠区如何合理经营畜牧业,防止草场退化,建立饲草料基地及扩大林地面积等措施。     

Formalizing agro-ecological engineering for future-oriented land use studies

Agriculture faces an array of interrelated problems that call for development of new and revision of existing cropping systems towards the multiple needs of the 21st century. Agro-ecological engineering approaches aimed at design and exploration of alternative land use systems at various scales may support the identification of appropriate land use options. Engineering approaches are based on mathematical representations of well-founded agro-ecological principles while taking into account available resources and prevailing land-related objectives. The goal of this paper is to contribute to the development of a formalized approach to engineer cropping systems at the land unit level that can be used as building blocks for systematic explorations of land use options at farm or regional scale. The approach for engineering cropping systems at the land unit level consists of three steps: (i) goal-driven design of cropping systems, (ii) quantification of biophysical production targets and (iii) definition of the optimal mix of inputs required to realize production targets. This paper describes the approach and illustrates it with examples from the Sudano-Sahelian zone of Mali. Explicit attention is paid to the required numerical tools and their application to analyze consequences of uncertainty in the performance of engineered cropping systems. Using numerical tools, uncertainty is made explicit with the aim to better manage or reduce it. Identification of uncertainty at the designer's desk allows taking uncertainty into account before applying engineered land use systems in regional model studies or testing such systems in practice. Problems related to the application of numerical tools are discussed, including the future role of agro-ecological engineering as independent discipline within agricultural science.