Submitted to: Subtropical Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 21, 2000
Publication Date: N/A
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, so the adaption of conservation tillage practices in vegetable production would be desirable. With-in-row weeds can be difficult to control in any tillage system, even with the use of pre- and post-emergence herbicides. In 1998, two sweet corn cultivars were grown in three on-going tillage systems, conventional tillage (CT), ridge tillage (RT), and no tillage (NT), with and without in-row weed removal in order to determine how well conservation tillage systems tolerated additional weed pressure. Marketable yields were reduced 18 percent when additional weeds were present in all tillage systems, but only the ear weights of the shorter-growing mid-season cultivar were reduced by RT and NT. The taller-growing cultivar shaded weeds better by intercepting more sunlight and reduced weed competition (biomass) underneath. Cultivar selection will be important if conservation tillage systems are to be successful in vegetable crop production.
In spring 1998, furrow-irrigated sweet corn cultivars, 'Sensor' and 'G-90' (Zea mays var. rugosa), were grown under two conservation tillage (CNT) systems in the presence or absence of weeds, and compared to conventionally-grown sweet corn, grown in the presence or absence of weeds. Tillage systems, consisting of conventional cultivation, ridge tillage, and no tillage, were in continuous rotation since fall 1994. Sweet corn yields were not influenced by CNT but the later-maturing 'G-90' had higher yields than did 'Sensor'. The presence of weed pressure reduced yield and ears/ha in 'G-90', but not in 'Sensor'. Weed pressure reduced 'Sensor', but not 'G-90' average ear weight. 'Sensor' ear weights were lowest when grown under no tillage. 'G-90' ear weights were not affected by CNT. Ear quality attributes, which included ear weight, length, diameter, dry matter, and incidence of earworm damage, were greater in 'G-90' than 'Sensor', but CNT had no influence on these attributes. 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. CNT increased weed biomass. Season soil moisture was lowest in the ridge tilled plots, but only in the 0-15 cm profile. Soil temperatures (unreplicated) at the 15 cm depth were similar between cultivar and tillage treatments over the growing season.