Submitted to: Journal of Vegetable Crop Production
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 1, 2002
Publication Date: February 1, 2003
Citation: Makus, D.J. 2003. SOIL BUT NOT SWEET CORN EAR NUTRIENTS ARE AFFECTED BY CONSERVATION TILLAGE. Journal of Vegetable Crop Production. 8(2):49-63. Interpretive Summary: Conservation tillage systems are used to reduce wind-blown soil erosion, improve soil quality, and reduce soil moisture loss between plantings. Vegetable crops are traditionally grown in soil which has been stirred up by plowing and cultivating. In a two-year study, two sweet corn cultivars were grown each year under furrow irrigation to evaluate three on-going tillage systems, conventional tillage (CVT), minimal or ridge tillage (RT), and no tillage (NT), in a semi-arid environment. Marketable yields and ear weights were only affected when shorter, early season cultivars were grown under NT compared to CVT. Ear phosphorus, and possibly N, K, S, and Fe in addition to the cumulative nutrient levels were reduced by conservation tillage in one of the two years. Soil nutrients at the fifth year were cycled to the top of the soil profile when NT was practiced and season soil moisture levels were higher in the upper 6 inches (1998). Yield and ear weights were not affected by RT, and if cultivars are selected which favorably compete with weed pressure, reduced tillage can be successfully used in commercial sweet corn production.
Technical Abstract: The sweet corn (Zea mays var. rugosa) cultivars, 'Champ' and 'Sensor' (1997) and 'Sensor' and 'G-90' (1998), were grown under three tillage systems, conventional cultivation (CT), minimum or ridge tillage (RT), and no tillage (NT), which had been maintained, as such, since fall 1994. Nitrogen (as NH4NO3), the only fertilizer used, was applied twice each season at 67 kg/ha. 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 differences in ear quality attributes, which included ear weight, length, diameter, dry matter, and incidence of earworm damage between cultivars, but tillage had very little affect 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 (unreplicated) 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, 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, the final year of the study, soil sampled at 0-5, 10-15, and 25-30 cm depth generally had higher concentrations of nutrients toward the surface, and NT soils had the steepest 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.