Preferential Water Flow Through Corn Canopy and Soil Water Dynamics Across Rows

Abstract

Small‐scale and spatially dependent variation in real‐time soil water dynamics, caused largely by agricultural practices, is not well understood. Objectives of this study were (i) to quantify the preferential stemflow vs. throughfall of water under rainfall and sprinkler irrigation during the closed corn (Zea mays L.) canopy period and from senescence to harvest, and (ii) to quantify in real time the corresponding row and interrow soil water dynamics under multiple annual no‐tillage and plow‐tillage corn experiments. Water redistribution through the corn canopy was studied for a 2‐yr period, with stemflow measured by placing flexible polyethylene bags on plants, and throughfall by placing jars between corn rows. Soil water dynamics was studied for a 3‐yr period, with multisensor capacitance probes and a monitoring system at five‐row and interrow positions for each tillage. Highly significant (P < 0.001) linear positive relationships were found between both stemflow (SF) and average throughfall (TF) to rainfall. An inverse third‐order relationship was found between the ratio of SF/TF and rainfall. Real‐time soil water dynamics data showed that the smaller rainfall events (<15 mm) resulted in a significant (P < 0.05) water infiltration advantage for the no‐tillage in‐row position compared with the no‐tillage interrow positions and compared with the plow‐tillage in‐row position. These results were consistent with the stemflow vs. throughfall data obtained under the closed corn canopy. Real‐time soil water dynamics vs. rainfall intensity at different soil layers showed the importance of rainfall and sprinkler irrigation redistribution induced by the canopy, type of tillage, and position across corn rows.