The influence of biochar particle size and concentration on bulk density and maximum water holding capacity of sandy vs sandy loam soil in a column experiment

摘要

Biochar application to agricultural soils has been proposed as a way to increase crop production by improving soil chemical and physical properties. Liming potential and improved nutrient exchange on biochar surfaces are the most reported mechanisms. Wherever crops experience drought stress, improvements in soil water holding capacity (WHC) might also be an important mechanism. However, reported effects on soil structure and WHC are mixed. Therefore, we studied the effects of biochar on soil bulk density (BD) and WHC in a laboratory column study using two agricultural soils from Portugal: a sandy and a sandy loam soil. Mixed woody feedstock was pyrolysed at 620 degrees C, creating a wettable biochar that was used unsorted as well as sieved into large (2-4 mm) and small (0.05-1.00 mm) particles, mixed into the soils at 1, 5, 10 and 20% (by volume), and incubated for 10 days at field capacity to allow aggregation. Soil samples were analysed for BD and WHC using soil columns.