Soil Nitrogen Mineralization Influenced by Crop Rotation and Nitrogen Fertilization

Abstract

N made available to crops that follow legumes in rotation. An estimate of soil mineralizable N is needed to determine crop While fertilization guides use total organic matter and needs for N fertilizer. The objective of this research was to estimate previous crop as indicators of N mineralization for the soil net N mineralization in soils maintained in continuous corn (Zea mays L.) (CC), corn-soybean [Glycine max (L.) Merr.] (CS), and coming season, a variety of direct and indirect lab methcorn-soybean-wheat (Triticum aestivum L.)/alfalfa (Medicago sativa ods may be used for more precise predictions (Fox and L.)-alfalfa (CSWA) rotations that have been managed since 1990 Piekielek, 1978; Hong et al., 1990). Laboratory tests with zero N (0N), low N (LN), and high N (HN) fertilization. Soil allow compositing and homogenizing soil samples to samples were taken from 0-to 20-cm depth in plots planted to corn decrease the standard deviation and required replicain 1998. In order to produce more realistic time-series data of net N tion. Aerobic incubation for 120 to 252 d is commonly mineralization, soils were incubated in filtration units in a variableused to estimate the size and decay rates of mineraliztemperature incubator (VTI) that mimicked field soil temperatures able N pools (Stanford and Smith, 1972; Cabrera and under a growing corn canopy. Rotation and N fertilization significantly Kissel, 1988). Temperature and matric potential of incuaffected net N mineralization in soil samples. Cumulative net N minerbated soils affect the rate and cumulative N mineralized. alized in a 189-d field temperature incubation averaged 133 Ϯ 6 kg ha Ϫ1 in CC, 142 Ϯ 5 kg ha Ϫ1 in CS, and 189 Ϯ 5 kg ha Ϫ1 in CSWA. Within ordinary field soil matric potentials from Ϫ1.85 Across rotations, average net N mineralized was 166 Ϯ 9 kg ha Ϫ1 in to Ϫ0.01 MPa, temperature has a greater influence on 0N plots, 147 Ϯ 10 kg ha Ϫ1 in LN plots, and 152 Ϯ 10 kg ha Ϫ1 in N mineralization than does matric potential (Zak et al., HN plots. Inclusion of a legume, particularly alfalfa, in the rotation 1999). Most N mineralization laboratory experiments increased net N mineralized. Generally, more net N was mineralized are incubated at 35ЊC, considered the ideal temperature from plots receiving no fertilizer N than from soil with a history of for maximum N mineralization. Nitrogen mineralized N fertilization. Variable-temperature incubation produced realistic in laboratory incubations at 35ЊC represents potential time-series data with low sample variability.

Nitrogen dynamics in soil management systems: II - mineralization and nitrification rates

“…In the 5-10 cm layer, the mineralization rate was lowest in the CT system, but did not differ from the other management systems (Figure 2). These lower rates probably occurred due to the immobilization of N fertilizer by soil microorganisms, which influenced the mineralization of organic N negatively, supporting the results of Carpenter-Boggs et al (2000), obtained in crop rotation systems involving corn and soybean.…”

Soil Nitrogen Transformations and Availability in Upland Pine and Bottomland Alder Forests

“…When N is less available, microbes actively mine recalcitrant organic matter to acquire it; whereas, in N rich environments, microbes can assimilate inorganic N without costly mineralization activity. Although the relationship between inorganic N availability and microbial activities have been reported to be both positive [50,51] and negative [52][53][54] in empirical studies mainly based on fertilization experiments in forests, wetlands, or agricultural land, a meta-analysis of Treseder [55] suggested that N addition reduced microbial biomass by 15% and, consequently, also microbial activities such as soil respiration. Those articles could provide a theoretical proof and empirical evidence supporting the decrease of net N mineralization under high NH4 + concentrations in the BAF.…”

Mineralização e desnitrificação do nitrogênio no solo sob sistema plantio direto

“…Diversos autores (TouchTon e hargrove, 1982, rice e SmiTh, 1984, PöTTKer e roman, 1994, lara caBezaS, 2001 afirmaram que a utilização de uréia no SPD não é uma fonte eficiente de N para o sistema devido a perdas por volatilização e, com o acúmulo de resíduos culturais em superfície com elevada relação C:N, favorece a imobilização do N pelos microrganismos do solo (carPenTer-BoggS et al, 2000).…”