PHYSICAL FRACTIONATION AND CARBON AND NITROGEN STOCKS IN SOIL AFTER POULTRY WASTE APPLICATIONS

ABSTRACT Residues from turkey production are often used as fertilizers in pastures near producing regions. These residues can contribute to the increase of carbon and nitrogen stocks in the soil. This study aimed to evaluate the cumulative effects of nine applications of turkey litter rates on C and N fractions and stocks in a Latossolo Vermelho distroférrico (Oxisol) cultivated under rotational grazing. The experimental area was divided into 16 pickets of 0.5 ha each and cultivated with Urochloa decumbens in a rotational grazing system. The treatments consisted of accumulated doses of turkey litter (38.3; 54.8 and 69.2 Mg ha−1), with applications carried out between 2008 and 2017, in addition to a control treatment, without application of this material. After nine years of application, total organic carbon (TOC) and total nitrogen (TN) stocks in the soil increased as turkey litter rates increased, reaching increments in the 0-0.2 m layer of 11.2 Mg ha−1 and 1.03 Mg ha−1, respectively, when compared to the control treatment. In the same 0-0.2 m layer, the maximum increments in carbon stock in particulate organic matter (POC) and nitrogen stock in particulate organic matter (N-POM) were obtained with the estimated total doses of 62 and 66 Mg ha−1, respectively. In addition to increasing the amount, the use of turkey litter improved the quality of the carbon present in the soil, since the carbon management index, in the 0-0.2 m layer, was increased by 124% when using the highest accumulated dose.

摘要：火鸡养殖产生的废弃物常被用作产区周边牧场的肥料，此类物料可提升土壤碳氮储量。本研究旨在评估9次施加火鸡垫料（turkey litter）的累积施用量对轮牧制度下种植的俯仰臂形草（Urochloa decumbens）的Latossolo Vermelho distroférrico（Oxisol，氧化土）中碳、氮组分及其储量的影响。试验区域划分为16个面积各为0.5公顷的试验小区，采用轮牧系统种植俯仰臂形草。试验设置累计施用量分别为38.3、54.8和69.2 Mg·ha⁻¹的火鸡垫料处理组，于2008年至2017年间分批次施加，另设不施加该物料的对照组。经过9年施加后，土壤总有机碳（Total Organic Carbon, TOC）与总氮（Total Nitrogen, TN）储量随火鸡垫料施用量提升而增加；在0~0.2 m土层中，相较于对照组，其储量增量分别可达11.2 Mg·ha⁻¹与1.03 Mg·ha⁻¹。在同一土层中，颗粒态有机碳（particulate organic carbon, POC）与颗粒态有机氮（nitrogen in particulate organic matter, N-POM）的储量增量最大值分别对应预估总施用量62 Mg·ha⁻¹与66 Mg·ha⁻¹。除提升储量外，施加火鸡垫料还可改善土壤碳组分质量，在0~0.2 m土层中，施加最高累计施用量时碳管理指数（carbon management index, CMI）提升了124%。