Description of the carbon mineralization of swine manure and oat straw in the soil through nonlinear models

Abstract

Agricultural management is a viable way for recycling animal residues in feedlots. Thesubstances that make up organic residues change the dynamics of the organic matter decompositionin the soil. Information on carbon mineralization curves allows seeking improvements in soil qualityand, consequently, in crop productivity. The Stanford & Smith Nonlinear Model is the most usedto describe C mineralization of organic residues in the soil. This model considers organic residuesare composed of substances that are mineralized exponentially. The Cabrera Model considers twofractions, one composed of substances that are mineralized exponentially and other composed ofmore resistant substances with constant mineralization. The objective of this work was to comparenonlinear models that describe carbon mineralization, considering residues on surface or incorporatedinto the soil. The data evaluated were from an experiment with oat straw, liquid swine manure, andswine litter bedding. The Stanford & Smith and Cabrera Models were used considering structure offirst order autoregressive errors - AR(1), when necessary. The fittings were compared using the AkaikeInformation Criterion (AIC). The Cabrera Model was more adequate to describe C mineralization infour treatments (soil + incorporated liquid swine manure; soil + oat straw on surface + liquid swinemanure on surface; soil + incorporated straw; and soil + straw on surface). The Stanford & SmithModel was better in three treatments (soil + incorporated straw + incorporated liquid swine manure;swine litter bedding on surface; and incorporated swine litter bedding). None of the models describedthe treatment soil + liquid swine manure on surface.Keywords: Decomposition. Half-life. Stanford & Smith Model. Cabrera Model.

Comparison of nonlinear models in the description of carbon mineralization in litter soil

“…The independence of errors was rejected for this treatment because the measurements were made in the same experimental unit, so the parameter ϕ was added to explain this correlation (TABLE 3), that is, for this treatment an adjustment with first-order auto-regressive error AR (1). Silva et al (2019a), Silva et al (2019b), and Hess and Schmidt (1995) also observed a correlation in errors when fitting nonlinear models to cumulative data of CO 2 mineralization of various organic residues in the soil. Estimates of parameters of the Stanford and Smith model and the half-life (t 1/2 ) with their respective 95% confidence intervals are listed in Table 2.…”

“…In fitting the Molina model (double exponential) to C mineralization data from soil under eucalyptus plantation, Barreto et al (2010) obtained non-significant parameters for the model, thus indicating that the process did not have two carbon compartments. On the other hand, Silva et al (2019a) reported two phases of carbon mineralization of the treatments soil + oat straw, soil + pig slurry, and soil + pig slurry + oat straw, in addition, Silva et al (2019b) observed the same behavior for soil + sewage sludge + oat straw. indicated that for all treatments and both models the errors were independent (p-value > 0.05), except for the Juma model fit to the Acacia soil treatment (p-value < 0.05).…”

“…The greater amount of organic matter and the presence of easily decomposing substances favor carbon mineralization at the beginning of the process, that is, the decomposition dynamics occur at decreasing rates, as the organic material is mineralized (PULROLNIK, 2009;MOREIRA;SIQUEIRA, 2006), consequently, the release of other nutrients to the soil occurs. These processes can be described by nonlinear models (PAULA et al, 2019;SILVA, 2005;SILVA et al, 2019a;SILVA et al, 2019b;ZEVIANI et al, 2012;OLIVEIRA et al, 2013). The knowledge of the carbon (C) mineralization dynamics in the soil is essential for the development of appropriate practices in the soil use, being indicative of the organic residues contributing to the demand of trees throughout the crop cycle (BARRETO et al, 2010;GODINHO et al, 2014).…”

“…In litter soils, it may be that the mineralization process has two phases of mineralization, one phase due to easily mineralizable substances and another phase due to the more resistant substances. In processes with two phases, the use of the Cabrera model has shown a good fit (PAULA et al, 2019;SILVA et al, 2019a;SILVA et al, 2019b;ZEVIANI et al, 2012;PEREIRA et al, 2009).…”

Comparison of nonlinear models for the description of carbon mineralization in degraded pasture soil and in soils with plant cover

“…É um modelo com dois parâmetros que representam o carbono potencialmente mineralizável e a constante de mineralização. O modelo Cabrera tem apresentado bons ajustes em processos que apresentam duas fases de mineralização, uma facilmente mineralizável com comportamento exponencial e outra resistente com comportamento constante (PAULA et al, 2020;PEREIRA et al, 2009;SILVA et al, 2020a;SILVA et al, 2019a;SILVA et al, 2019b;ZEVIANI et al, 2012). Outro modelo utilizado é o não linear Juma (PAULA et al, 2019;PEREIRA et al, 2005), com dois parâmetros que apresentam interpretação prática direta, carbono potencialmente mineralizável e tempo de meia-vida, respectivamente.…”