Exchangeable Aluminum As a Criterion for Liming Leached Mineral Soils1
01 Mar 1970-Soil Science Society of America Journal (John Wiley & Sons, Ltd)-Vol. 34, Iss: 2, pp 252-254
About: This article is published in Soil Science Society of America Journal.The article was published on 1970-03-01. It has received 301 citations till now. The article focuses on the topics: Saturation (chemistry) & Lime.
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01 Jan 1982
2,974 citations
TL;DR: In this paper, the authors bring together examples of low-input soil management technology adapted to well-drained, acid, inherently infertile soils of the American tropics classified mainly as Oxisols and Ultisols.
Abstract: Publisher Summary The purpose of this chapter is to bring together examples of low-input soil management technology adapted to well-drained, acid, inherently infertile soils of the American tropics classified mainly as Oxisols and Ultisols. Soil taxonomy terminology, including soil moisture regimes, is used. The outcome of the race between world food production and population is determined in the tropics, where most of the world's undernourished people live. The applicability of high-input soil management technologies, however, diminishes in marginal lands where soil and water constraints are not easily overcome at low cost. The rising price spiral of petroleum-related products since has limited the economic feasibility of soil management technologies based on the intensive use of purchased inputs, particularly for farmers with limited resources in the tropics. The term ‘‘low’’ is used in relation to “high”-input technology where the application of fertilizers and amendments largely eliminate chemical soil constraints. The identification of plant species and ecotypes tolerant to the main acid soil stresses allows the development of low-input soil management systems for Oxisol and Ultisol regions where socioeconomic constraints prevent the widespread application of large quantities of lime and fertilizers. The basic approach is to use plants adapted to acid soil constraints, to maximize the use of fertilizers and lime needed to produce about 80% of their maximum yield, and to take advantage of favorable attributes of acid, infertile Oxisols and Ultisols.
527 citations
TL;DR: In this article, the authors assess strategies for the enhancement and exploitation of biological nitrogen fixation with attention to the likely timescales for realization of benefits in agriculture and propose a strategy for the breeding of legumes for N2-fixation and rhizobial strain selection with less potential to increase inputs of fixed N than alleviation of environmental stresses or changes in farming systems.
Abstract: Strategies for the enhancement and exploitation of biological nitrogen fixation are assessed with attention to the likely timescales for realization of benefits in agriculture. Benefits arising from breeding of legumes for N2-fixation and rhizobial strain selection have less potential to increase inputs of fixed N than alleviation of environmental stresses or changes in farming systems to include more legumes. Genetic engineering may result in substantial enhancement of N2-fixation, particularly if the ability to fix N2 is transferred to other crops but these are long-term goals. Immediate dramatic enhancements in inputs from N2-fixation are possible simply by implementation of existing technical knowledge. Apart from the unfortunate political and economic barriers to the use of agricultural inputs, better communication between researchers and farmers is required to ensure proper focus of research and development of appropriate technologies. Legumes must be considered within the context of the farming systems within which they are grown and not in isolation. Proper integration of legumes requires a good understanding of the role of the legume within the system and a better understanding of the relative contributions of N sources and of the fates of fixed N.
388 citations
TL;DR: In this article, a comprehensive and updated review of lime requirements for improved annual crop production on Oxisols is provided, and experimental data are provided to make this review as practical as possible for improving crop production.
Abstract: The greatest potential for expanding the world's agricultural frontier lies in the savanna regions of the tropics, which are dominated by Oxisols. Soil acidity and low native fertility, however, are major constraints for crop production on tropical Oxisols. Soil acidification is an ongoing natural process which can be enhanced by human activities or can be controlled by appropriate soil management practices. Acidity produces complex interactions of plant growth‐limiting factors involving physical, chemical, and biological properties of soil. Soil erosion and low water‐holding capacity are major physical constraints for growing crops on tropical Oxisols. Calcium, magnesium, and phosphorous deficiencies or unavailabilities and aluminum toxicity are considered major chemical constraints that limit plant growth on Oxisols. Among biological properties, activities of beneficial microorganisms are adversely affected by soil acidity, which has profound effects on the decomposition of organic matter, nutrient mineralization, and immobilization, uptake, and utilization by plants, and consequently on crop yields. Liming is a dominant and effective practice to overcome these constraints and improve crop production on acid soils. Lime is called the foundation of crop production or “workhorse” in acid soils. Lime requirement for crops grown on acid soils is determined by the quality of liming material, status of soil fertility, crop species and cultivar within species, crop management practices, and economic considerations. Soil pH, base saturation, and aluminum saturation are important acidity indices which are used as a basis for determination of liming rates for reducing plant constraints on acid soils. In addition, crop responses to lime rate are vital tools for making liming recommendations for crops grown on acid soils. The objective of this chapter is to provide a comprehensive and updated review of lime requirements for improved annual crop production on Oxisols. Experimental data are provided, especially for Brazilian Oxisols, to make this review as practical as possible for improving crop production.
375 citations
01 Jan 1984
276 citations