Soil potassium bioavailability and root growth factors in ridge and conventionally tilled soils.

摘要

Plant K uptake and early season growth are diminished where the ridge tillage planting system has been used for relatively long periods on some west-central Minnesota soils. Field studies were conducted for three years to evaluate the effect of ridge tillage and chisel plow planting systems on potassium (K) nutrition and growth of corn. Root system characteristics, K uptake, and shoot dry matter accumulation were measured for two corn hybrids (Pioneer 3732 and Pioneer 3737) that have different susceptibilities to the tillage-associated K deficiency. Root activity measurement using non-radioactive trace elements was compared to a conventional soil core method to measure root length. Although variability of the non-radioactive tracer method was high, differences due to treatment factors in the experiment could be measured. However, as implemented, the tracer method did not identify hybrid architectural differences found using the conventional root coring technique. Root system architecture was hybrid dependent although rates of K influx were not. One hybrid (Pioneer 3737) had more roots located near the soil surface and in the interrow area. Root architecture of Pioneer 3732 was oriented more vertically and had a greater percentage of roots deeper in the profile. The data suggest the lateral spreading of Pioneer 3737 roots made it less susceptible to the tillage-associated K deficiency by increasing positional access to bioavailable K. Soil temperatures were approximately 1{dollar}spcirc{dollar} C lower in the ridge tillage planting system compared to the chisel plow system, and less soil water was present in the row in ridge tillage. These conditions could reduce root activity and K diffusion in the soil.