Talore Deribe G, Tesfamariam Eyob H, Hassen Abubeker, Du Toit J C O, Klampp Katja, Jean-Francois Soussana
Department of Animal and Wildlife Sciences, University of Pretoria, Pretoria, South Africa.
Department of Plant Production and Soil Sciences, University of Pretoria, Pretoria, South Africa.
J Sci Food Agric. 2016 Apr;96(6):1945-52. doi: 10.1002/jsfa.7302. Epub 2015 Jul 3.
Little is known about how basic soil properties respond to contrasting grazing intensities in the Karoo biome, South Africa. The aim of this study was to investigate impacts of long-term (>75 years) grazing at 1.18 heads ha(-1) (heavy; CGH), 0.78 heads ha(-1) (light; CGL), and exclosure on selected soil properties. Soil samples were collected to a depth of 60 cm from the long-term experimental site of Grootfontein Agricultural Development Institute, Eastern Cape. The samples were analyzed for C, N, bulk density and infiltration rate, among others.
Generally, heavy and light grazing reduced soil N storage by 27.5% and 22.6%, respectively, compared with the exclosure. Animal exclusion improved water infiltration rate and C stocks significantly (P < 0.05), which was 0.128, 0.097, and 0.093 Mg ha(-1) yr(-1) for exclosure, CGL and CGH, respectively. Soil penetration resistance was higher for grazing treatments in the top 3-7 cm soil layer but for exclosure at the top 1 cm soil surface.
Although livestock exclusion has the potential to improve C sequestration, a sufficient resting period for 1-2 years followed by three consecutive grazing years at light stocking rate would be ideal for sustainable livestock production in this arid region of South Africa.
对于南非卡鲁生物群落中基本土壤性质如何响应不同放牧强度，人们了解甚少。本研究的目的是调查长期（>75年）以1.18头/公顷（重度；CGH）、0.78头/公顷（轻度；CGL）放牧以及围栏禁牧对选定土壤性质的影响。从东开普省格罗特方丹农业发展研究所的长期试验地采集了深度达60厘米的土壤样本。对样本进行了碳、氮、容重和入渗率等分析。
总体而言，与围栏禁牧区相比，重度和轻度放牧分别使土壤氮储量减少了27.5%和22.6%。禁牧显著提高了水分入渗率和碳储量（P < 0.05），围栏禁牧区、CGL和CGH的碳储量分别为0.128、0.097和0.093 Mg ha(-1) yr(-1)。在土壤表层3 - 7厘米处，放牧处理的土壤穿透阻力较高，但在土壤表层1厘米处，围栏禁牧的土壤穿透阻力较高。
虽然禁牧有可能提高碳固存能力，但在南非这个干旱地区，为实现可持续畜牧业生产，理想的做法是先有1 - 2年的充足休耕期，然后连续三年以轻度载畜率放牧。
