Calculation of nitrogen mineralization and leaching in fallow soil using a simple dynamic model

Abstract

Summary Simple models describing nitrogen processes are required both to estimate nitrogen mineralization in field conditions and to predict nitrate leaching at large scales. We have evaluated such a model called LIXIM, which allows calculation of nitrogen mineralization and leaching from bare soils, assuming that these are the dominant processes affecting N in bare soil. LIXIM is a layered, functional model, with a 1‐day time step. Input data consist of frequent measurements of water and mineral N contents in soil cores, standard meteorological data and simple soil characteristics. The nitrate transport is simulated using the ‘mixing‐cells’ approach. The variations in N mineralization with temperature and moisture are accounted for, providing calculation of the ‘normalized time’. An optimization routine is used to estimate the actual evaporation and the N mineralization rates that provide the best fit between observed and simulated values of water and nitrate contents in all measured soil layers. The model was evaluated in two field experiments (on loamy and chalky soils) including treatments, lasting 9–20 months. The water and nitrate contents in soil were satisfactorily simulated in both sites, and all treatments, including a 15N tracer experiment performed in the loamy soil. In the chalky soil, the calculated water balance agreed well with drainage results obtained in lysimeters and independent estimates of evaporation. At both sites, N mineralization was reduced by the incorporation of crop residues (wheat or oilseed rape straw); the amounts of nitrogen immobilized varied between 20 and 35 kg N ha−1. In the treatments without crop residues, the mineralization rate followed first‐order kinetics (against normalized time) in the loamy soil, and zero‐order kinetics in the chalky soil. In the latter soil, the mineralization kinetics calculated in situ were close to the kinetics measured in laboratory conditions when both were expressed against normalized time.

Nitrato no solo com a aplicação de dejetos líquidos de suínos no milho em plantio direto

“…Para melhor estabelecer o potencial real dos dejetos de suínos em causar contaminação das águas subterrâneas com nitrato, seria interessante estender a coleta de solo para camadas além da zona de absorção do sistema radicular do milho, apesar das dificuldades metodológicas para tal. O uso de modelos matemáticos, baseados em medidas de N mineral no solo e de variáveis climáticas, durante a fase experimental, tem se mostrado uma estratégia promissora para a previsão das perdas de NO 3 -por lixiviação (Mary et al, 1999).…”

A Dynamic Decision-Making Tool for Calculating the Optimal Rates of N Application for 40 Annual Crops While Minimising the Residual Level of Mineral N at Harvest

“…The formalisms and the set of parameters describing the different processes in AzoFert ® were derived from models generated by academic research, particularly from STICS [23] and LIXIM [36,37]. The number of parameters was kept to a minimum, and input data (27 to 40, depending on the crop) were selected according to their availability at the farm level and, of course, their importance.…”

“…In soils in which organic matter accumulates below the ploughed layer, the extra N mineralisation is calculated as a fixed extra 10% of the N mineralised in the ploughed layer. The potential rate of mineralisation is calculated from the organic N pool of the considered soil layer (Norg) and the rate of mineralisation of this pool (k 2 ), which depends on the clay and limestone concentrations in the soil [21][22][23].…”

Dynamiques de décomposition des résidus de cultures sur des exploitations pratiquant l'agriculture de conservation en région Grand Est, France

“…Nous avons choisi d'utiliser la méthode des jours normalisés, largement utilisée dans plusieurs modèles de simulation de C et N (Brisson et al, 2009 ;Mary et al, 1999). Cette approche permet de transformer chaque jour calendaire en une durée exprimée par jour à une température et une humidité de référence, ou « jour normalisé » (JN).…”