Weed dynamics productivity and resource use efficiencies as influenced by weed management and conservation tillage in maize wheat rotation

Abstract

newline The field experiment was conducted during kharif 2018 to rabi 2019-20 with fifteen treatment combinations of a continuing experiment since 2013-14, out of which five tillage treatments viz. CT-CT, CT-ZT, ZT-ZT, ZT-ZTR and ZTR-ZTR (CT, conventional; ZT, zero and ZTR, zero tillage with residue incorporation) and three weed management treatments viz. H-H, IWM-IWM and HW-HW; (H, herbicide; IWM, integrated weed management; HW, hand weeding) in maize-wheat cropping sequence at Research Farm of Department of Agronomy, CSKHPKV. The soil of the test site was silty clay loam in texture, acidic in reaction, high in organic carbon and P, medium in K and low in N. In maize, Ageratum conyzoides and Commelina benghalensis were the major weeds constituting 23.8 and 21.4 per cent, respectively of thetotal weed flora at maximum weed population stage during kharif 2018, whereas, Echinochloa colona and Digitaria sanguinalis were the major weed constituting about 25.3 and 14.6 per cent of the total weed population, respectively during kharif 2019. In wheat, Avena ludoviciana and Daucus carota were the major weeds constituting 26.4 and 25.1 per cent, respectively during 2018-19 and 25.2 and 24.4 per cent, respectively during 2019-20. ZT+IWM-ZTR+IWM remained statistically alike with ZTR+IWM-ZTR+IWM resulted in significantly lower total weed count at 60 DAS in maize over rest of the treatments. However, ZTR+HW-ZTR+HW resulted in lowest dry matter accumulation during 2018 and 19, respectively. In wheat crop, ZT+H-ZT+H and CT+H-ZT+H resulted in lowest total weed count during 2018-19 and 2019-20. Around 70% of the weed seedling in weed seed bank study emerged at 0-5 cm compared to 6-10 cm depth. Soil microwave treatment was found to be the potential treatment to exhaust the weed seed bank. ZTR+IWM-ZTR+IWM recorded significantly higher yield and yield attributes, highest wheat grain equivalent and highest net returns, gross returns and benefit cost ratio. Among different tillage treatments, ZT-ZT, CT-ZT and ZT-ZTR remained statistically at par with each other for maximum energy use efficiency and energy productivity. However among weed management treatments, H-H had highest energy efficiency and energy productivity. ZTR+IWM-ZTR+IWM had higher economic nutrient use efficiency, nitrogen use efficiency, nutrient harvest index, apparent N recovery, apparent nutrient recovery and partial nutrient balance in maize-wheat cropping system during 2018-19 and 2019-20. ZTR+IWM-ZTR+IWM had highest soil physical (water holding capacity and field capacity), chemical (organic carbon), sequestrated carbon and soil microbial population (fungi, actinomycetes, phosphate solublizing microbes and azotobacter) and enzymatic activity (microbial biomass carbon, dehydrogenase, urease, acid and alkaline phosphatise activity) during both the experimental years. ZTR+IWM-ZTR+IWM improved soil health by increasing soil physical, chemical and microbial properties which results to higher soil microbial index and soil quality index. Based on two years study and keeping into consideration the burning of crop residues in maize-wheat system especially maize residue of maize in Himachal Pradesh, we may advocate to adopt conservation agricultural practices viz. ZTR+H-ZTR+H or ZTR+IWM ZTR+IWM for higher productivity, profitability, soil health and resource use efficiencies.