No Tillage and Strip Tillage Effects on Plant Performance, Weed Suppression, and Profitability in Transitional Organic Broccoli Production

Abstract

<jats:p>Organic no-till and strip-till systems have gained attention because of their reported capacity to enhance soil health and suppress annual weeds. This study, conducted at the Horticulture Research Station, Ames, IA, over 2 years (2013–14 and 2014–15) compared a cover crop–based no tillage (NT), strip tillage (ST), and conventional tillage (CT) in transitional organic broccoli (<jats:italic>Brassica oleracea</jats:italic> L. var. <jats:italic>italica</jats:italic>) production, with data collected on broccoli yield and quality, plant health, weed suppression, soil temperature, and cost of production. A cover crop mixture of cereal rye (<jats:italic>Secale cereal</jats:italic>e L.) and hairy vetch (<jats:italic>Vicia villosa</jats:italic> Roth.) was seeded in all plots in September, and was ended by rolling and crimping (NT and ST) or soil incorporation (CT) in late spring the following year. Each whole-plot tillage treatment was split into two subplot fertility treatments—one based entirely on organic preplant granular fertilizer, and the other split between preplant granular fertilizer and postplanting fertigation—to test the effect of fertigation on yield and plant growth under the typically nitrogen (N)-limited reduced tillage conditions. In 2014, yield of broccoli was highest in CT treatments, averaging 5.4 t·ha<jats:sup>−1</jats:sup>, with no difference between ST and NT treatments. In 2015, yields were equal among tillage treatments, averaging 20.0 t·ha<jats:sup>−1</jats:sup>. Changing the timing of fertilizer application through the use of fertigation did not affect yield. Weed density and biomass were lowest in the between-row (BR) regions of NT and ST plots in 2014, indicating effective early-season weed suppression. In 2015, NT and ST plots generally had lower weed biomass and density compared with CT plots, but weed growth in BR and in-row (IR) regions of NT and ST plots was similar. Soil temperature was highest in CT plots throughout the year, and higher in ST than in NT plots only during some periods. While production costs did vary slightly across treatments, profit per hectare was most strongly affected by yield. Our findings suggest that cover crop–based organic NT and ST systems may be viable options for organic broccoli growers.</jats:p>

Cover Crop Biomass Production in Temperate Agroecozones

“…Studies that specifically compared tillage system effects on CC biomass production reported that tillage method did not generally affect CC biomass production in 20 of 22 studies using a variety of CC species including radish, hairy vetch, and rye (Yaffa et al, 2000;Sainju et al, 2005;Schomberg et al, 2006;Petersen et al, 2011;Evans et al, 2016). One of the two remaining studies found that CC biomass was 2.3 Mg ha -1 greater with strip till and 0.8 Mg ha -1 lower with conventional tillage compared to no-till (Jokela and Nair, 2016), while the other study found that tillage had variable effects ranging from neutral to increased biomass production (Price et al, 2016). Our review suggests that CC biomass production may not depend on tillage in most studies, which is somewhat surprising because tillage can move crop residues below the soil surface and can improve seed-soil contact compared to no-till.…”

Legume species not spatial arrangement influence cover crop mixture effects in strip‐tilled organic cabbage

“…Shank and coulter ST equipment, as used in our trials, can lead to rough and nonuniform seedbed conditions when operating in grass crowns and present challenges for crop establishment (Luna & Staben, 2002). Others have used an additional ST pass in late fall after cover crop establishment to reduce interference with spring ST at the time of cash crop planting (Jokela & Nair, 2016a). The ST and planting tools used and crop type (direct seeded vs. transplanted) could be important considering this potential advantage of segregated plantings.…”

“…capitata ) (Haramoto & Brainard, 2012; Hefner et al., 2020), broccoli ( Brassica oleracea var. italica ) (Jokela & Nair, 2016a), bell pepper ( Capsicum annuum L.) (Delate et al., 2008; Jokela & Nair, 2016b), sweet corn ( Zea mays L.) (Lowry & Brainard, 2017), cucurbits, and others (Leavitt et al., 2011; Lilley & Sanchez, 2016). Reduced N availability under RT is variously attributed to temperature and moisture mediated reductions in N mineralization rates (Dou et al., 1994; Grandy & Robertson, 2006), increases in N 2 0 emissions (MacKenzie et al., 1997), increased volatilization of surface‐applied fertilizers when not incorporated, and/or immobilization of N in surface residues (Grandy et al., 2006; Ismael et al., 1994; Mulvaney et al., 2010).…”

Evaluation of the Agronomic Performance of Organic Processing Tomato as Affected by Different Cover Crop Residues Management

“…In these systems, cover crops are terminated without incorporating residues into the soil, thus leaving a thick mulch into which the subsequent cash crop is planted. This requires the necessity to produce large cover crop biomass as well as a good management of their residues to provide maximum weed suppression and nutrients adjustments, e.g., reduce immobilization, enhance N release and synchronization with plant needs [9]. Weed management and nutrient availability are two factors known to challenge the performance of crops in organic no-till production.…”