Soil But Not Sweet Corn Ear Nutrients Are Affected by Conservation Tillage

ABSTRACT Sweet corn (Zea mays var. rugosa Bonaf.) production was evaluated under reduced tillage in a semi-arid, subtropical environment. Cultivars Champ and Sensor (1997) and Sensor and G-90 (1998) were grown under conventional cultivation (CT), minimum or ridge tillage (RT), and no tillage (NT), which had been maintained since fall 1994. Sweet corn yields and ear weights were reduced by NT in 1997, but were not affected in 1998 when longer season cultivars were planted. There were generally cultivar differences in ear weight, length, diameter, dry matter, and incidence of earworm damage, but tillage had very little effect on these attributes. Data collected in 1998 indicated that cultivars supported different weed species underneath their canopies. ‘Sensor’ allowed more light penetration and sustained higher weed biomass than did the taller ‘G-90’ plants. Weed biomass was higher in RT and NT. Seasonal soil moisture (1998) was lowest in the RT plots, but only in the 0–15 cm profile. The 1998 soil temperatures at the 15 cm depth were similar between cultivars and tillage treatments over the growing season. Cultivar ear nutrients differed in P, S, NO3, Ca and Fe in both years. Ear nutrients were not affected by tillage system in 1998, but in 1998 N (P = 0.12), K (P = 0.14), P (P = 0.05), S (P = 0.09), and Fe (P = 0.16) were lowest in NT-grown ears. Cumulative nutrient levels tended (P = 0.08) to be lowest in 1998 NT-grown ears. In 1998, soil sampled at 0–5, 10–15, and 25–30 cm depth generally had higher levels of nutrients toward the surface, and NT soils had the greatest nutrient gradients, with the exception of Na and NO3. Total soil salts were reduced by RT and NT, but C:N ratio remained unchanged between tillage systems. Proper cultivar selection is important for the successful production of sweet corn grown with reduced tillage in subtropical environments.