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Impacts of Integrated Crop-Livestock System on Soil Surface Greenhouse Gas Fluxes at a Farm Scale in South Dakota

机译：南达科他州农场规模的农牧综合系统对土壤表层温室气体通量的影响

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摘要

Grazing and cover crops (CC) can impact soil nutrient cycling but may increase the greenhouse gas (GHG) emissions from soils. However, little is known about their impacts on soil properties and soil surface GHG emissions in an integrated crop-livestock system (ICLS) in South Dakota, USA. The present study was conducted at a farm scale at the Research Farm of South Dakota State University, Brookings, South Dakota, to assess the impact of cover crops and grazing on soil pH, electrical conductivity (EC), and bulk density (BD), and soil surface carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes. Study treatments included grass dominated mixture CC and broadleaf dominated mixture CC, both with and without grazing, and the control field with no CC or grazing. Soil BD samples were collected using a 5 cm diameter and 5 cm height core from 0-5 and 5-15 cm depths. Additionally, soil samples were collected from 0-5, 5-15, and 15-30 cm depths using a manual push probe to measure the soil EC and pH. The BD was conducted using the core method. Soil pH and EC was measured using a suspended sample consisting of soil (air-dried) and water (soil:water), with an Orion Star pH and EC meter. Soil surface GHG fluxes were monitored using polyvinyl chloride (PVC) static chambers (25 cm diameter x 15 cm height) installed in the field. Gas samples were taken daily in 2016, and weekly, depending on weather conditions, in 2017.;The results showed that grazing significantly increased soil pH and EC for all depths. The grazing treatment significantly decreased soil BD for the lower depth. Legume CC significantly decreased pH for all depths, while grass CC decreased pH for the lower two depths. Legume CC significantly decreased EC at the surface and lower depth, while grass CC only lowered EC at the lower depth. The CC treatment showed no significant effect on BD at any depth. Grazing treatment showed no significant results for CO2 or CH4 fluxes for either sampling year. Grazing did not show any effect on N 2O fluxes for 2016, but significantly increased fluxes during 2017. Neither CC treatment had any effects on N2O nor CH4 fluxes. However, in 2016, the legume CC significantly increased CO2 emissions and both CC treatments increased CO2 fluxes compared to fallow (control) for the 2017 season. Time effects on soil CH4 fluxes were not significant, however, were significant for CO2 and N2O fluxes. Soil CO2 and N2O fluxes increased as soil and air temperature increased, and soil moisture increased.;The present study concluded that grazing significantly impacted the selected soil properties such as pH, EC, and BD, however, CCs are less likely to impact the selected properties in the short-term (first year of study). The grazing treatment significantly increased soil N2O fluxes but did not impact soil CO2 and CH4 fluxes. The CC treatment significantly increased soil CO2 fluxes compared to the fallow but did not impact soil CH4 and N2O fluxes. Time significantly impacted soil CO2 and N2O fluxes but did not impact CH4 fluxes. A positive correlation between CO2 and N2O fluxes, soil and air temperature, and soil moisture was identified. Since some soil properties and GHG emissions were negatively impacted by the grazing and CC in the ICLS during this short-term study, further research for the long-term effects of grazing and CC should be conducted.
机译：放牧和覆盖作物（CC）会影响土壤养分循环，但可能会增加土壤中的温室气体（GHG）排放。但是，在美国南达科他州的农作物－畜牧综合系统（ICLS）中，它们对土壤特性和土壤表层温室气体排放的影响知之甚少。本研究是在南达科他州布鲁金斯市南达科他州立大学研究农场的农场规模上进行的，目的是评估有盖作物和放牧对土壤pH，电导率（EC）和容重（BD）的影响，以及土壤表面的二氧化碳（CO2），甲烷（CH4）和一氧化二氮（N2O）通量。研究处理包括有草或无草的以草为主的混合物CC和以阔叶为主的混合物CC，以及无CC或无草的对照田。使用直径为5厘米，高度为5厘米，深度为0-5和5-15厘米的岩心采集土壤BD样品。此外，使用手动推杆从0-5、5-15和15-30 cm深度收集土壤样品，以测量土壤EC和pH。使用核心方法进行BD。使用Orion Star pH和EC计，使用由土壤（风干）和水（土壤：水）组成的悬浮样品测量土壤的pH和EC。使用现场安装的聚氯乙烯（PVC）静态室（直径25厘米x高15厘米）监测土壤表面的温室气体通量。根据天气情况，2016年每天取样一次气体，2017年每周取样一次;结果表明，放牧显着提高了所有深度的土壤pH和EC。放牧处理在较低深度下显着降低了土壤BD。在所有深度，豆科植物的CC均显着降低了pH值，而在较低深度的两个深度中，草类CC均降低了pH值。豆科植物CC显着降低了表层和较低深度的EC，而草类CC仅降低了较低深度的EC。 CC治疗对任何深度的BD均无明显影响。在两个采样年中，放牧处理对CO2或CH4流量均无显着影响。放牧对2016年的N 2O通量没有任何影响，但在2017年显着增加了通量。CC处理均不影响N2O和CH4的通量。然而，与2017年休耕（对照）相比，豆类CC在2016年显着增加了CO2排放，并且两种CC处理均增加了CO2通量。对土壤CH4通量的时间影响并不显着，但是对于CO2和N2O通量而言，显着。土壤CO2和N2O通量随着土壤温度和空气温度的升高以及土壤水分的增加而增加。短期（学习的第一年）中的属性。放牧处理显着增加了土壤N2O通量，但不影响土壤CO2和CH4通量。与休耕相比，CC处理显着增加了土壤CO2通量，但不影响土壤CH4和N2O通量。时间显着影响土壤CO2和N2O通量，但不影响CH4通量。确定了CO2和N2O通量，土壤和气温以及土壤湿度之间的正相关关系。由于在这项短期研究中，某些土壤特性和温室气体排放受到ICLS中放牧和CC的负面影响，因此应进一步研究放牧和CC的长期影响。

著录项

  • 作者

    Douville, Brant.;

  • 作者单位

    South Dakota State University.;

  • 授予单位 South Dakota State University.;
  • 学科 Soil sciences.;Climate change.
  • 学位 M.S.
  • 年度 2017
  • 页码 91 p.
  • 总页数 91
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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