Carbon and Nitrogen Mineralization and Crop Uptake of Nitrogen from Six Green Manure Legumes Decomposing in Soil

Abstract

Sweden). Carbon and nitrogen mineralization and crop uptake of nitrogen from six green manure legumes decomposing in soil. Received Febr. 20, 1991. Acta Agric. Scand. 41: 243-252, 1991.Carbon and nitrogen mineralization from six green-manure legumes w s studied in an incubation experiment. The values measured \vcrc fitted to a two-component and a onecomponent first-order model, respectively. Estimated parameters \\ere compared. During I I5 days of incubation approximately 30-35% of total N in white clover, black medic and subterranean clover \\as mineralized. Red clover and Persian clover mineralized only 20% and egyptian clover 17%. White clover, black medic and subterranean clover showed a net mineralization during the whole incubation period. Red clover. Persian clover and egyptian clover showed apparently an initial immobilization followed by a net mineralization after approximately 2 weeks. In a pot experiment, N uptake in rye grass from the six legumes was measured and comparisons were made with the incubation experiment after corrections for temperature differences. The amount of N harvested in the pot experiment \im approximately 90% of the net N mineralization during decomposition. K~J words: Eifolirtrii pratense L., T. repens L., 7. resrrpinntirni L., 7. olexandrinrrrn L., 7. srrbterraneion L., hledicago lrrpulina L., mineralization rate, k-valrre.

Pasture type and fertilization effects on soil chemical properties and nutrient redistribution

“…It has been documented that for decomposing materials, the lower the C:N ratio the more rapid is the mineralization (Wedin and Tilman 1990). The roots and herbage of legumes usually have C:N ratios in the range of 13:1 to 20:1 (Marstorp and Kirchman 1991) and thus will tend to mineralize N more readily than grasses. Mytton et al (1993) also suggest that the presence of legumes such as white clover (Trifolium repens L.), in swards could improve soil structure, which, in turn, may increase mineralization rate.…”

Consorciação de plantas de cobertura antecedendo o milho em plantio direto: I - Dinâmica do nitrogênio no solo

“…Considerando esses valores e as quantidades de N adicionadas pela leguminosa (Quadro 1), é possível estimar uma mineralização líquida de N nesse período de aproximadamente 0,30 kg de N para cada kg de N-ervilhaca adicionado em 1998 e de 0,36 kg de N para cada kg de N-ervilhaca adicionado em 1999. Esses valores de mineralização líquida são próximos daquele relatado por Marstorp & Kirchmann (1991) para as leguminosas Trifolium repens L. e Medicago lupina L. de 0,36 kg de N para cada kg de N adicionado. A estimativa da mineralização e da imobilização de N a partir da diferença entre as quantidades de N mineral dos tratamentos com e sem plantas de cobertura (pousio) é feita, considerando que os resíduos culturais das plantas de cobertura não influem na taxa de mineralização do N da matéria orgânica do solo ("priming effect").…”

Organic Carbon Decomposition in Soil Amended With Organic Compost From Slaughterhouse Residues

“…Thus, if the added organic material exceeds this limit, it will be shared between two pools: protected (C pc ) and unprotected (C uc ) added compost. The employment of a double exponential model to describe the decomposition kinetics of the native soil organic matter is justified due to its different degrees of stabilization at a range of environmental conditions (Bernal & Kirchmann, 1992;Boyle & Paul, 1989;Marstorp & Kirchmann, 1991). Presence of pools of organic matter with different decomposition rates is visualized at C-CO 2 evolution curves (Figure 2).…”