Soil hydraulic properties influenced by agroforestry and grass buffers for grazed pasture systems

• Published in: Journal of soil and water conservation Vol. 63; no. 4; pp. 224 - 232
• Main Authors: Kumar, S, Anderson, S.H, Bricknell, L.G, Udawatta, R.P, Gantzer, C.J
• Format: Journal Article
• Language: English
• Published: Ankeny, IA Soil and Water Conservation Society 01.07.2008; Soil & Water Conservation Society
• Subjects: agroforestry; Agronomy. Soil science and plant productions; Analysis; Animals; Biological and medical sciences; Buffer zones (Environmental protection); Carbon sequestration; Cattle; conservation buffers; Festuca arundinacea; Forest soils; Fundamental and applied biological sciences. Psychology; grasses; Grazing; grazing intensity; Hydraulics; infiltration (hydrology); Influence; Kummerowia stipulacea; Lespedeza; Nonpoint source pollution; pastures; Physical properties; Physics, chemistry, biochemistry and biology of agricultural and forest soils; pollution control; Populus; Pore size; porosity; rotational grazing; saturated hydraulic conductivity; Soil chemistry; soil properties; Soil research; Soil science; Soil sciences; soil water content; soil water retention; Trees; Trifolium; Water and solute dynamics; Missouri; United States; North America; America; Vegetative filter strip; Soil water retention; Soil moisture; Hydraulic conductivity; Buffer system; Grazing; Pore size; Soil water properties; Saturated medium; Pasture; Resource management; agroforestry buffer-grass buffer-pore size distribution-saturated hydraulic conductivity-soil water retention; Water holding capacity; Agroforestry
• ISSN: 0022-4561; 1941-3300; 1941-3300
• DOI: 10.2489/jswc.63.4.224

Agroforestry buffers have been introduced in temperate areas to improve water quality and diversify farm income. The objective of this study was to evaluate saturated hydraulic conductivity and water retention for soils managed under rotationally grazed (RG) pasture, continuously grazed (CG) pasture, grass buffers (GB), and agroforestry buffers (AgB). Pasture and GB areas included red clover ( Trifolium pretense L.) and lespedeza ( Kummerowia stipulacea Maxim.) planted into fescue ( Festuca arundinacea Schreb.) while AgB included Eastern cottonwood trees ( Populus deltoids Bortr. ex Marsh.) planted into fescue. Water retention data were measured at -0.4, -1.0, -2.5, -5.0, -10, -20, and -30 kPa (-0.058, -0.145, -0.363, -0.725, -1.45, -2.90, -4.35 pounds per square inch [psi]) soil water pressures using 76 mm (3.00 in) diameter by 76 mm long cores from the 0 to 10 cm, 10 to 20 cm, 20 to 30 cm, and 30 to 40 cm (0 to 3.94 in, 3.94 to 7.87 in, 7.87 to 11.81 in, and 11.81 to 15.75 in) depths. Soil bulk density was 12.6% higher for the RG and CG treatments (1.41 and 1.45 g cm -3 [88.02 and 90.52 lb ft -3 ]) than the GB and AgB treatments (1.25 and 1.29 g cm -3 [78.03 and 80.53 lb ft -3 ). Soil water content at high soil water potentials (0 and -0.4 kPa) was greater in the buffer treatments relative to the other treatments for the 0 to 10 cm soil depth. Soil macroporosity (>1,000 µm [>0.0394 in] diameter) was 5.7, 4.5, and 3.9 times higher, respectively, for the AgB, GB, and RG treatments compared to the CG treatment for the 0 to 10 cm soil depth. Buffer treatments had greater macroporosity (>1,000 µm diameter), coarse (60 to 1,000 µm [0.00236 to 0.0394 in] diameter) and fine mesoporosity (10 to 60 µm [0.000394 to 0.00236 in] diameter), but lower microporosity (<10 µm diameter) compared to RG and CG treatments. Saturated hydraulic conductivity values for GB and AgB treatments were 16.7 times higher (56.95 vs. 61.33 mm h -1 [2.24 vs. 2.41 in hr -1 ]) compared with RG and CG (3.98 vs. 3.11 mm h -1 [0.157 vs. 0.122 in hr -1 ]). This study illustrates that agroforestry and grass buffers maintained higher values for soil hydraulic properties compared to grazed pasture systems.