Impacts of Pecan Waste Products on the Quality of Semiarid Soils.

This study shows the prospects of improving soil quality using pecan waste products in the Desert Southwest U.S. Two soils of different textures (sandy loam and clay loam), collected from irrigated fields in southern New Mexico were amended with ground waste pecan products consisting of shells (PS), husks (PH), and pecan shell biochar (PSB). The amended soils were compared with non-amended soils which served as control (CO) treatments. Ground waste pecan products were applied to the soil at a rate of 20 ton/ha, and each amended soil was packed inside a cylindrical ring at a bulk density of 1.2 Mg m³. The samples were moistened and incubated for 3 week in a growth chamber. After 3 weeks, the soils were saturated within the rings, and soil moisture sensors were installed in each sample and were allowed to dry out for 8 days under room temperature. Soil moisture content was logged at hourly interval each day. After 8 days, the sensors were removed from the soil rings, and the samples were broken up and air dried. The experimental design was a complete randomized block design with treatments replicated four times. Measurements performed on the air dried samples included the wet aggregate stability (WAS), permanganate oxidizable carbon (POXC), organic matter content and selected soil chemical parameters. Results showed that the impacts of the amendments were soil dependent. PH, PS and PSB led to significant increases in soil water holding capacity compared to the CO treatment in the sandy loam soil, while these amendments did not improve soil moisture holding capacity in the clay loam soil. PH and PS led to significant increase in WAS in both soils while PSB did not improve WAS. PH and PS led to significantly higher POXC in the clay loam soil but not in the sandy loam.