Influence of Subsurface Irrigation and Organic Additions on Top and Root Growth of Field Corn1

Abstract

AbstractNumerous attempts have been made to increase root proliferation by modifying soil profiles possessing undesirable chemical and physical properties.Field and laboratory studies were conducted over a 5‐year period on an Evesboro loamy sand (mesic, coated Typic Quartzipsamments) soil from Delaware to determine the effect of organic additions and type of irrigation on corn (Zea mays L.) grain yield, root distribution, and on selected soil properties. The study also sought to determine if organic additions would increase the effectiveness of subsurface irrigation. Organic additions, made only in the 1st year of the study, consisted of 10 ✕ 40 cm chisel (C) openings at 76 cm intervals which were filled with solid waste (SW) and/or poultry manure (PM) at 65 metric tons/ha. No attempt was made to superimpose corn rows directly above the chisel openings. Irrigation types were subsurface (SSI), and trickle irrigation (TI). Grain yields were significantly higher in C + SSI than in C + TI treatments. Chiseling + SSI increased the average 5‐year corn yield 4,300 kg/ha over C alone which demonstrated the pronounced effect that SSI had on yield. Organic additions had no signifciant effect on grain yields, although yields for the C + SW treatment were numerically higher than for the C + PM treatment each year of the study, and the former averaged 1,150 kg/ha higher over the 5‐year period. The C + SW treatments also produced higher yields than the control (NC). Chiseling, without incorporation of organic materials (C) was no more effective than leaving the soil undisturbed (NC). Organic additions enhanced root growth more than yield of corn. The subsoil was essentially devoid of roots without chiseling or organic additions. The highest CEC and organic matter levels at the end of the 5‐year study were found in the organic addition trench adjacent to the SSI lines. Corn roots proliferated in this region and in most cases enveloped the irrigation lines. Lateral as well as vertical movement of Ca, K, Mg, and P occurred with the lowest concentrations occurring in the plow layer. Movement of plant nutrients laterally from the organic addition trench into the surrounding subsoil probably contributed to root extension and could be significant in terms of nutrient utilization.