Evaluation of Established Perennial Clover Living Mulch and Soil Management Effects on Weed Suppression, Soil Health, and Broccolini Production for the Northern Great Plains

Abstract

Vegetable cropping systems have long been reliant on the use of tillage to prepare favorable seedbeds and manage weed pressure. Tillage degrades soil structure, decreases water infiltration and leads to compaction. Due to recent droughts across the central United Stated, it is important for water conservation to improve infiltration and avoid run off and erosion. Changes in weather patterns not only influence drought conditions but bring heat waves that have made early and late planted cool season crops in the brassica family prone bolting, leading to unmarketable produce and economic losses for farmers. This 2023 and 2024 study was designed to evaluate living mulches of three established clover varieties, ‘Domino’ white clover (WC) (Trifolium repens), ‘Aberlasting’ white x kura clover (KC) (T. repens x ambiguum), and ‘Dynamite’ red clover (RC) (Trifolium pratense), and a bare ground control (BG); in combination with in-row soil management of tilled only (T), no-till (NT), tilled with fabric (TF), and no-till with fabric (NTF); and three broccolini cultivars, ‘Melody’ (ME), ‘BC1611’ (BC), and ‘Burgundy’ (BU). These 16 treatment combinations were evaluated for their impact on soil water infiltration, soil compaction, soil temperature and moisture; broccolini plant health metrics, growth and yield; and biomass of clover and weeds throughout two growing seasons. We hypothesized that the use of NT clover living mulch treatments would improve soil health quality and suppress weed biomass to reduce the need for tillage, and the use of in-row landscape fabric would guard against yield losses from clover living mulch competition. 2023 results showed that all three clover treatments improve soil water infiltration compared to the BG plots while there were no differences in soil resistance measurements in all treatments. Living mulch suppressed weed growth and biomass accumulation throughout the season with a significant decrease in weeds among WC, KC, and RC plots compared to BG conditions. The use of landscape fabric in the NTF treatment prevented significant yield loss in all three broccolini varieties and was comparable to the T and TF while the NT led to significant losses in yield. These results show that clover living mulch can be used to suppress weed and improve soil health. ‘Melody’ is smaller condensed variety that is quick to begin producing florets while ‘BC1611’, and ‘Burgundy’ are full sized and slower maturing. Broccolini varieties showed tolerance to heat stress that would make broccoli unmarketable. Living mulch can compete with a cash crop to reduce yield so it is important to use it in conjunction with a stress tolerant crop such as broccolini to prevent yield loss. This allows producers to spread out their economic risk while improving soil health using clover living mulch