The Integrated Effects of Biostimulant Application, Mechanical Weed Control, and Herbicide Application on Weed Growth and Maize (Zea mays L.) Yield

Abstract

A field trial was conducted (2020–2021) in a randomized complete block design arranged according to the split-plot design to evaluate the integrated effects of an alternative fertilization practice based on the application of a microbial biostimulant in combination with different weed control methods on weed growth and maize productivity. Two fertilization practices, conventional (CF) and alternative (AF), formed the main plots. The CF supplied maize with 160 kg N ha−1. The AF included a foliar application of the biostimulant NitroStim®, which contains N2-fixing bacteria (1 × 1012 colony forming units; CFU L−1) along with a 50% lower fertilizer incorporation rate (80 kg N ha−1). Four weed control treatments formed the subplots: one inter-row mechanical cultivation (M1), two inter-row mechanical cultivations (M2), tembotrione application (99 g a.i. ha−1; H), and an untreated control (CON). Combined over the years (p ≥ 0.05), fertilization, weed control, and their interactions affected (p ≤ 0.05) weed density and biomass, maize grain yield, and nitrogen partial factor productivity (PFPN). The AF reduced weed biomass by 28% compared to the CF. M1 resulted in a high value (389 g m−2). M2 and H reduced weed biomass compared to (M1 ≥ 70%). Weed biomass dropped below 35 g m−2 in the AF × H and AF × M2 subplots. Observations on weed density were similar. The AF resulted in 12 and 56% higher maize grain yield and PFPN than the CF, respectively. M2 increased grain yield by 18 and 25% compared to M1 and CON, respectively, and was not different from H. Moreover, AF × H and AF × M2 were the highest-yielding interactions (≥12,000 kg grain ha−1). AF × M2 increased PFPN by 56, 58, 64, and 67% compared to CF × H, CF × M2, CF × M1, and CF × CON, respectively, while AF × H resulted in similar PFPN.