Root Life Extended by a New Climate SMART Long-term Soil Technology Promoting Production and Protecting the Environment

Frequent plant water deficits, followed by irrigation or rainfall, cause root malfunction and death; then regrow additional new roots. Frequent root growth, death and regrowth diminish plant production by competing for aboveground plant photoassimilates. Volumetric soil water content (VWC), below 10% VWC in sand soils at matric potentials of –100 hPa, diminish soil water conductivity to plant roots by three orders of magnitude in sands. Even lower VWCs are achieved in sands within a few days following the best irrigation scheduling. Hysteretically regenerating root systems, experiencing literally dozens of plant water deficits, become gigantic carbon sinks stifling maximum production potential by the best hybrid cultivars.

Installing a long-term soil water retention technology (SWRT) system, below the plant root zone, coupled with prescription-controlled irrigation scheduling, maintains optimal conditions extending root life and function without wasteful losses of plant carbon. This report identifies how combining soil biophysics with engineering dramatically reduced irrigation energy, maintain excellent soil water supplies, reduce soil evaporation, and prohibit deep leaching of agricultural chemicals enabling greater plant resilience to changing climates.

Five years of field testing reiterated how root to shoot ratios depended upon season and vegetative stage. However, root lengths and volumes of highest producing maize planted on irrigated sands, improved by SWRT membranes, were smaller than irrigated or nonirrigated controls. In 2016, when maize grain yield approached 21.2 MT/ha, on irrigated SWRT membranes, root lengths and volumes were 30% and 73% lower, during the mid-vegetative (V8) stages, than irrigated and non-irrigated control sands without SWRT membranes. Despite greater root development by maize and vegetables, yields for irrigated and non-irrigated rainfed control treatments were 14% to 27% lower than irrigated and rainfed SWRT improved sand.