在最佳管理条件下牛羊放牧会显著增加沉积物流失吗？来自英国北威克农场平台的证据。

Does cattle and sheep grazing under best management significantly elevate sediment losses? Evidence from the North Wyke Farm Platform, UK.

作者信息

Pulley S, Cardenas L M, Grau P, Mullan S, Rivero M J, Collins A L

机构信息

Sustainable Agriculture Sciences, Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB UK.

Bristol Veterinary School, University of Bristol, Langford, Somerset BS40 5DU UK.

出版信息

J Soils Sediments. 2021;21(4):1875-1889. doi: 10.1007/s11368-021-02909-y. Epub 2021 Mar 13.

DOI:10.1007/s11368-021-02909-y

PMID:34720744

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC8550719/

Abstract

PURPOSE

Intensive livestock grazing has been associated with an increased risk of soil erosion and concomitant negative impacts on the ecological status of watercourses. Whilst various mitigation options are promoted for reducing livestock impacts, there is a paucity of data on the relationship between stocking rates and quantified sediment losses. This evidence gap means there is uncertainty regarding the cost-benefit of policy preferred best management.

METHODS

Sediment yields from 15 hydrologically isolated field scale catchments on a heavily instrumented ruminant livestock farm in the south west UK were investigated over ~ 26 months spread across 6 years. Sediment yields were compared to cattle and sheep stocking rates on long-term, winter (November-April), and monthly timescales. The impacts of livestock on soil vegetation cover and bulk density were also examined. Cattle were tracked using GPS collars to determine how grazing related to soil damage.

RESULTS

No observable impact of livestock stocking rates of 0.15-1.00 UK livestock units (LU) ha for sheep, and 0-0.77 LU ha for cattle on sediment yields was observed at any of the three timescales. Cattle preferentially spent time close to specific fences where soils were visually damaged. However, there was no indication that livestock have a significant effect on soil bulk density on a field scale. Livestock were housed indoors during winters when most rainfall occurs, and best management practices were used which when combined with low erodibility clayey soils likely limited sediment losses.

CONCLUSION

A combination of clayey soils and soil trampling in only a small proportion of the field areas lead to little impact from grazing livestock. Within similar landscapes with best practice livestock grazing management, additional targeted measures to reduce erosion are unlikely to yield a significant cost-benefit.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11368-021-02909-y.

摘要

目的

集约化牲畜放牧与土壤侵蚀风险增加以及随之对水道生态状况产生的负面影响有关。虽然人们推广了各种缓解措施以减少牲畜影响，但关于载畜率与量化泥沙流失之间关系的数据却很匮乏。这一证据空白意味着对于政策优先选择的最佳管理措施的成本效益存在不确定性。

方法

在英国西南部一个配备了大量仪器的反刍动物养殖场，对15个水文隔离的田间尺度集水区在6年中约26个月的泥沙产量进行了调查。将泥沙产量与长期、冬季（11月至4月）和月度时间尺度上的牛和羊的载畜率进行了比较。还研究了牲畜对土壤植被覆盖和容重的影响。使用GPS项圈跟踪牛群，以确定放牧与土壤破坏之间的关系。

结果

在三个时间尺度中的任何一个上，均未观察到绵羊载畜率为0.15 - 1.00英国牲畜单位（LU）/公顷以及牛载畜率为0 - 0.77 LU/公顷对泥沙产量有明显影响。牛优先在靠近特定围栏的地方活动，这些地方的土壤有明显受损迹象。然而，没有迹象表明牲畜在田间尺度上对土壤容重有显著影响。在大部分降雨发生的冬季，牲畜被圈养在室内，并且采用了最佳管理措施，再加上土壤侵蚀性较低的黏性土壤，这可能限制了泥沙流失。