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

Runoff and sediment yields were measured from eight field plots (40 m(2)) o ver a three year period to determine the effect of peanut cropping practice s and canopy cover conditions on runoff and sediment loss. Plots were locat ed on a Tifton loamy sand, and were exposed to four 30 min simulated rainfa ll sequences (I = 63.5 mm h(-1)) four to eight times per growing season. Ru noff and sediment losses were measured from four soil cover conditions: con tinuous fallow, bare bedded, single row peanuts (Arachis hypogea L), and tw in row peanuts (2 to 4 peanut rows per 2 m wide bed). percent cover (PC) an d leaf area index (LAI) increased to a maximum then leveled off as plants m atured 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 fo r twin row peanuts). LAI values for single and twin row peanuts were relate d 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 a nd as much as 63 times less sediment loss than continuous fallow or bare be dded plots. Twin row peanut plots had as much as three times less runoff an d sediment loss than single row peanut plots. Sequence-based erodibility va lues 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(- 1) ha(-1) mm(-1) (3 yr mean = 12.9, s.d. = 11.6), respectively. Soil loss r atios (SLR) ranged from 0.001-2.61. SLRs decrease to a low for cropstage 3 when percent canopy cover was greatest (DSP = 81-107), then increased as pe anut plants mature 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 con serving valuable natural resources.