Nitrogen Release from Surface‐Applied Cover Crop Residues: Evaluating the CERES‐N Submodel

Abstract

Further improvement of residue decomposition models may help to optimize the use of N released from cover crop residues. CERES models are widely used to simulate crop‐soil systems and have a common subroutine that describes N dynamics (CERES‐N). In this work, we tested CERES‐N with results from a litterbag study over 120 d in which crimson clover (Trifolium incarnatum (L.), rye (Secale cereale( L.), wheat (Triticum aestivum( L.), and oat (Avena sativa L.) residues were allowed to decompose on the soil surface. The field data were used to (i) evaluate the original CERES‐N and a modification of CERES‐N that allows users to enter actual sizes for the carbohydrates, cellulose, and lignin pools and (ii) determine the best‐fitting rate constants for decomposition of the carbohydrates and cellulose pools in the original CERES‐N and in CERES‐N with user‐supplied pool sizes. CERES‐N with the original rate constants or with rate constants and parameters proposed by other workers either underestimated (root mean square error RMSE = 1.23 g N m−2) or overestimated (RMSE = 2.18 g N m−2) N remaining in the crop residues after 120 d of decomposition. CERES‐N with user‐supplied pool sizes improved the simulation of N remaining after 120 d (RMSE = 0.69 g N m−2), but the simulated values generally tended to overestimate the field data. The best‐fitting rate constants for carbohydrates and cellulose pools were 0.67 and 0.021 d−1, respectively, for the original CERES‐N (RMSE = 0.77 g N m−2), and 0.17 and 0.011 d−1 for CERES‐N with user‐supplied pool sizes (RMSE = 0.55 g N m−2). Future work should further evaluate these fitted rate constants under field conditions.

Approaches for increasing nitrogen and water use efficiency simultaneously

“…Crop residues retain water and reduce soil temperature (Quemada and Cabrera, 2002). Decomposition rates of crop residues covering the soil are lower than incorporated residues, the risk of ammonia volatilization increases when stubble and fertilizers remain on the soil surface, and larger N immobilization is expected in conservation tillage (Quemada et al, 1997). Because of these factors, optimum fertilization is even more important with conservation than with conventional tillage (Wang et al, 2011).…”

Evaluating uncertainty in climate change impacts on crop productivity in the Iberian Peninsula

“…A complete description of the methodology used for these simulations and preliminary results can be found in Guereña et al (2001), Mínguez et al (2004Mínguez et al ( , 2007 and Olesen et al (2007). Briefly, CERES wheat and maize models (Ritchie & Otter 1985, Jones & Kiniry 1986, within the DSSAT 3.5 frame, Tsuji et al 1994), previously calibrated for various Iberian locations (Mariscal 1993, Rebollo 1993, Iglesias & Mínguez 1995, Quemada et al 1997, López-Cedrón et al 2005, were used to perform simulations for the control period and the A2 scenario using daily outputs from RCMs. Maximum and minimum temperature, solar radiation, precipitation, wind speed and relative humidity at surface level were formatted according to weather files of the crop models, thus applying the 'direct use' method.…”

Modelling nitrogen mineralization from manures: representing quality aspects by varying C:N ratio of sub-pools

“…Thus allowing the distribution of carbon between the three FPOOLs to be a model input that characterizes the organic substrate will alter the rate of net N mineralization (as shown by Quemada and Cabrera, 1995;Quemada et al, 1997). However changing the pool sizes alone cannot alter whether a source exhibits initial net N mineralization or immobilization (since this is determined by the C:N ratio of the substrate).…”