Effects of peanut cropping practices and canopy cover conditions on runoff and sediment yield

ABSTRACT:

Runoff and sediment yields were measured from eight field plots (40 m²) over a three year period to determine the effect of peanut cropping practices and canopy cover conditions on runoff and sediment loss. Plots were located on a Tifton loamy sand, and were exposed to four 30 min simulated rainfall sequences (I =63.5 mm h⁻¹) four to eight times per growing season. Runoff and sediment losses were measured from four soil cover conditions: continuous fallow, bare bedded single row peanuts (Arachis hypogea L), and twin row peanuts (2 and 4 peanut rows per 2 m wide bed). Percent Cover (PC) and leaf area index (LAI) increased to a maximum then leveled off as plants matured or were harvested. PC for single and twin row peanuts was related to days since planting (DSP) (r =0.96 for single row peanuts and r =0.98 for twin row peanuts). LAI values for single and twin row peanuts were related to PC (r =0.98 for single row peanuts and r =0.94 for twin row peanuts). Single and twin row peanut plots had as much as eight times less runoff and as much as 63 times less sediment loss than continuous fallow or bare bedded plots. Twin row peanut plots had as much as three times less runoff and sediment loss than single row peanut plots. Sequence-based erodibility values calculated from continuous fallow plots (K_FC) and bare bedded plots (K_BB) ranged from 4–24 (3 yr mean =11.3, s.d. = 5.3) and 2–36 kg ha h MJ ha⁻¹ mm⁻¹ (3 yr mean =12.9, s.d. =11.6), respectively. Soil loss ratios (SLR) ranged from 0.01–2.61. SLRs decreased to a low far cropstage 3 when percent canopy cover was greatest (DSP = 81–107), then increased as peanut plants matured or were harvested Results show how management practices, such as twin row peanuts, can maximize peanut canopy development early in the growing season and minimize the time in which bare soil is vulnerable to a runoff producing rainstorm, thus reducing runoff and soil loss and conserving valuable natural resources.