Influence of two organic amendments on the soil physical properties, soil losses, sediments and runoff water quality

Organic soil amendments are increasingly being examined for their potential use in preventing soil losses. The influence of two organic wastes (cotton gin crushed compost, CC, and poultry manure, PM) applied during a period of four years on a Xerollic Calciorthid under dryland conditions near to Seville (Guadalquivir Valley, Andalusia, Spain) on soil physical properties (structural instability and bulk density), soil loss (at 60 and 140 mm h− 1, respectively) and nutrient losses (organic carbon, NO3−–N, NH4+–N, P and K) in runoff water with the intention of observing possible eutrophication risks in waters, and sediments were studied. CC and PM were applied annually at rates of 3560 and 7120 kg organic matter ha− 1 yr− 1, respectively. Both organic wastes reduce aggregate instability, bulk density and soil loss. In detail and compared with the control soil (no organic treatment), CC and PM at the higher dose reduced aggregate instability by 21% and 17.8%, respectively, bulk density by 19.6% and 16.9%, respectively, and soil loss under simulated rain at 140 mm h− 1 by 29.2% and 25%, respectively. Nutrient losses in the runoff water and sediments were higher in organic-amended soils than in the control soil, particularly in the case of the PM-amended soils. The lower N/P ratios in runoff water produced by CC and PM treatments suggest a lower eutrophication risk in water. The variability in these results may be due to the different chemical natures of the wastes added to soil.