The Use of Winter Forage Crops and Dairy Manure to Improve Soil Water Storage in Continuous Corn in Southern Idaho

Quantifying soil water storage by changes in management practices, such as double cropping, manure application, and reduced tillage, in semi-arid and irrigated crop production areas is important for agricultural production. We investigated the effects of winter forage crops (triticale), dairy manure, and tillage on soil physical characteristics (soil water storage, infiltration, runoff, saturated hydraulic conductivity, and bulk density) and silage corn yield in calcareous silty loam soils in Southern Idaho for six years, from 2016 to 2021. Soil water storage was measured every 15 cm using a neutron probe down to 150 cm, and infiltration and runoff were measured using a Cornell Sprinkle Infiltrometer. Soil water storage tended to be lower for winter forage crop plus solid dairy manure, likely due to increased crop water use. Infiltration rate, runoff, and saturated hydraulic conductivity did not improve with winter forage crops or solid dairy manure. Rainfall before runoff was highest for winter forage crop plus solid dairy manure, suggesting that those plots were drier compared to the control. During the six years of the study, only three of those years saw treatment differences in silage corn yields, with yields being the highest for solid dairy manure only. Combined triticale and silage corn yield was higher in three years for winter forage crop plus solid dairy manure. Reduced tillage practices did not improve soil water storage, soil physical properties, or dry biomass yield (silage corn or silage corn plus winter forage crop). Based on these findings, using winter forage crops may be beneficial to increase total dry biomass yields in dairy systems that would like to increase their forage production, however it is not advised if a producer is only looking to increase silage corn production or in limited precipitation or irrigation areas.