Chapter 16

Chapter 16 - Nutrient Management Goals of Nutrient...

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Nutrient Management Goals of Nutrient Management Maximize economic return on nutrients Efficient use and conservation of nutrient resources Maintain or improve soil quality Maintain or improve water quality Soil and Water Quality Water quality is affected by nutrient losses from soil. The general recommendation is Input rate = crop use rate + other losses But at feedlots or similar operations, nutrient inputs (feed) > local crop use. There are about 4 kg manure / kg body mass in- crease. Thus, disposal of excess nutrients is a problem. Effect of buffer strip width on reducing the con- centration of N and P in runoff. Cover crops A few best management practices BMPs These reduce runoff and erosion. They also add organic matter and if the cover crop is a legume it adds N to the soil. The uptake of NO 3 - by cover crops also reduces leaching. Buffer strips Along streams and lake borders, consist of grass and thatch or trees and litter. Buffer strips reduce runoff flow velocity and increase: particulate settling, adsorption of chemicals by soil and residue, chemical degradation and nutrient uptake. This BMP is suitable where fertilizer, including manure or sludge, is applied and in logging. Herbicide-dessicated vetch in cotton. Conservation tillage Defined as tillage that leaves > 30 % of soil surface with residue, reduces runoff and erosion. The benefits of cover crops are compounded when used with conservation tillage. The width of the buffer strip depends on slope, soil, runoff volume, sediment load and type of vegetation.
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Crop rotations Break cycles of weeds, disease and insects and provide varied organic residues that encourage microbial diversity. Inclusion of a legume in the rotation adds N. Effect of incusion of a legume in a corn rotation on corn yields. Organic Sources of Nutrients Manures Plant nutrient composition is highly variable depending on animal, feed and storage of manure. Typically, N varies from 2 to 5 %; P from ½ to 2 %; and K from 1 to 3 %. The high water content of manure adds cost and hassle its use. Industrial and Municipal Wastes
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This note was uploaded on 01/08/2012 for the course AGRO 2051 taught by Professor Gaston during the Fall '08 term at LSU.

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Chapter 16 - Nutrient Management Goals of Nutrient...

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