Advances in Agronomy 

About: Advances in Agronomy is an academic journal published by Elsevier BV. The journal publishes majorly in the area(s): Soil water & Agriculture. It has an ISSN identifier of 0065-2113. Over the lifetime, 947 publications have been published receiving 136499 citations.

The Chemistry of Submerged Soils

Abstract: Publisher Summary This chapter discusses the chemistry of submerged soils. The chemical changes in the submerged materials influence: (a) the character of the sediment or soil that forms, (b) the suitability of wet soils for crops, (c) the distribution of plant species around lakes and streams and in estuaries, deltas, and marine flood plains, (d) the quality and quantity of aquatic life, and (e) the capacity of lakes and seas to serve as sinks for terrestrial wastes. The single electrochemical property that serves to distinguish a submerged soil from a well-drained soil is its redox potential. The redox potential of a soil or sediment provides a quick, useful, semiquantitative measure of its oxidation–reduction status. Two recent developments have stimulated interest in the chemistry of submerged soils: the breeding of lowland rice varieties, with a high yield potential, and the pollution of streams, lakes, and seas, by domestic, agricultural, and industrial wastes. The chemistry of submerged soils is valuable: (a) in understanding the soil problems, limiting the performance of high-yielding rice varieties, and (b) in assessing the role of lake, estuarine, and ocean sediments as reservoirs of nutrients for aquatic plants and as sinks for terrestrial wastes.

A review of biochar and its use and function in soil

Abstract: Agricultural activities and soils release greenhouse gases, and additional emissions occur in the conversion of land from other uses. Unlike natural lands, active management offers the possibility to increase terrestrial stores of carbon in various forms in soil. The potential to sequester carbon as thermally stabilized (charred) biomass using existing organic resource is estimated to be at least 1 Gt yr − 1 and “biochar,” defined by its useful application to soil, is expected to provide a benefit from enduring physical and chemical properties. Studies of charcoal tend to suggest stability in the order of 1000 years in the natural environment, and various analytical techniques inform quantification and an understanding of turnover processes. Other types of biochar, such as those produced under zero-oxygen conditions have been studied less, but costs associated with logistics and opportunity costs from diversion from energy or an active form in soil demand certainty and predictability of the agronomic return, especially until eligibility for carbon credits has been established. The mechanisms of biochar function in soil, which appear to be sensitive to the conditions prevailing during its formation or manufacture, are also affected by the material from which it is produced. Proposed mechanisms and some experimental evidence point to added environmental function in the mitigation of diffuse pollution and emissions of trace gases from soil; precluding the possibility of contaminants accumulating in soil from the incorporation of biochar is important to ensure safety and regulatory compliance.

A critical evaluation of traits for improving crop yields in water-limited environments.

Abstract: Publisher Summary This chapter evaluates traits for improving crop yield in water-limited environments. The chapter describes the components of yield and the determinants of survival against which the proposed and demonstrated contributions by traits are critically assessed. Both modern and subsistence agriculture are differentiated mainly by the degree of risk that can be tolerated. Many traits have been proposed for improving the performance of drought-affected crops. Putative traits are more effective in enhancing drought resistance and contributing to grain yield in water-limited environments. The potential value of a trait depends upon the crop and the moisture environment in which it is grown. The chapter presents simulation models, which are very powerful tools for critically assessing the value of putative traits. However, more work is needed in the development and testing of suitable models, and in their application for this purpose. Use of near-isogenic populations as opposed to isogenic lines also appears to hold great promise.

Nutrient cycling and soil fertility in the grazed pasture ecosystem

Abstract: Publisher Summary This chapter reviews the cycling of nutrients within pasture soils. The major emphasis is on the central role of the grazing animal in influencing soil fertility, particularly in the dung and urine patches. In addition, the progress is reviewed that has been made in modeling the cycling of nutrients in pasture systems. Nutrients are partitioned differently between dung and urine, with K being excreted mainly in urine; P, Ca, and Mg are excreted principally in dung and N and S are excreted in both forms. Nutrients returned in excreta can be in inorganic and organic forms, depending on the particular nutrient being considered. For some nutrients (e.g., P and S) significant mineralization of ingested organic forms occurs during passage through the animal, whereas much of the N is excreted in the readily available organic urea form. From the present knowledge of the major nutrient inputs and losses for the grazed pasture system and an understanding of the pathways of nutrient flux within the system and some key measurements, simple mass balance nutrient models for various pasture systems can be constructed. Such simple models have been used to calculate site-specific maintenance fertilizer requirements of pastures based on the amount of nutrient required to replace losses in the soil (e.g., through fixation and leaching) and losses by animal transfer and in animal products.

Enhancing nitrogen use efficiency in crop plants

Abstract: Nitrogen is the most limiting nutrient for crop production in many of the world's agricultural areas and its efficient use is important for the economic sustainability of cropping systems Furthermore, the dynamic nature of N and its propensity for loss from soil‐plant systems creates a unique and challenging environment for its efficient management Crop response to applied N and use efficiency are important criteria for evaluating crop N requirements for maximum economic yield Recovery of N in crop plants is usually less than 50% worldwide Low recovery of N in annual crop is associated with its loss by volatilization, leaching, surface runoff, denitrification, and plant canopy Low recovery of N is not only responsible for higher cost of crop production, but also for environmental pollution Hence, improving N use efficiency (NUE) is desirable to improve crop yields, reducing cost of production, and maintaining environmental quality To improve N efficiency in agriculture, integrated N management strategies that take into consideration improved fertilizer along with soil and crop management practices are necessary Including livestock production with cropping offers one of the best opportunities to improve NUE Synchrony of N supply with crop demand is essential in order to ensure adequate quantity of uptake and utilization and optimum yield This paper discusses N dynamics in soil‐plant systems, and outlines management options for enhancing N use by annual crops