Influence of conservation tillage and weed management practices on growth and yield attributes of maize (Zea mays L.) in Sandy Loam soil of Odisha

Introduction

Maize (Zea mays L.) is one of the major cereal crops grown worldwide because of its high productivity, wide adaptability and diverse uses as food, animal feed and industrial raw material. Its growth and productivity are greatly influenced by soil conditions, moisture availability, nutrient supply and weed competition. Therefore, the choice of tillage system is important for proper crop establishment and growth, as well as for maintaining soil moisture, managing crop residues and controlling weeds. Continuous intensive tillage can gradually deteriorate soil structure, reduce soil organic matter and increase the risk of soil erosion. Conservation agriculture offers a more sustainable alternative by minimizing soil disturbance, retaining crop residues on the soil surface and improving resource-use efficiency. However, conservation tillage may not always result in higher maize yields, particularly during the initial years of adoption. Studies have shown that its effectiveness depends largely on climatic conditions, soil characteristics, residue management and other crop-management practices. Poor weed management, in particular, can reduce the potential benefits of reduced tillage [1][2][3][4] . Residue mulching can further improve the effectiveness of zero tillage by conserving soil moisture, reducing evaporation, moderating soil temperature and suppressing weed emergence. Studies on tropical maize production systems have reported improvements in grain yield and biomass with mulching, although the response varies with rainfall, soil fertility, mulch quality and management practices [5] . Conservation agriculture may also alter weed populations and species composition over time, making integrated and location-specific weed management essential [3,6] . In Odisha, maize is cultivated under diverse soil and climatic conditions, including sandy loam soils where moisture conservation and timely weed control are particularly important. Therefore, the present experiment was conducted during the rabi season of 2020-21 to evaluate conventional and zero-tillage systems, with and without paddy-straw mulch, combined with different weedmanagement practices for their effects on maize growth and yield attributes.

Materials and Methods

Experimental site and season

The experiment was conducted during rabi 2020-21 at the AICRP on Weed Management Block, Central Farm, Department of Agronomy, Odisha University of Agriculture & Technology (OUAT), Bhubaneswar, Odisha, India. The experimental soil was sandy loam, with pH 5.6, bulk density 1.5 Mg m⁻³, organic carbon 6.3 g kg⁻¹, available nitrogen 218.28 kg ha⁻¹, available phosphorus 21.36 kg ha⁻¹ and available potassium 127.28 kg ha⁻¹. The maize hybrid used was 'Nilesh hybrid'.

Experimental design and treatments

The experiment was arranged in a split-plot design with three replications. Tillage practices were assigned to main plots and weed-management practices to subplots.

Tillage operations

Under zero tillage, soil disturbance was minimized and sowing was carried out by opening narrow furrows with a power-tiller-operated zero-till drill. The same sowing method was followed under ZT+M, along with the application of paddy straw mulch at 5 t ha⁻¹. About 5-10% of the residue from the previous rice crop was also retained in the field. Under conventional tillage, the field was prepared by disc ploughing, followed by 2-3 harrowings and planking to obtain a suitable seedbed for sowing.

Observations and calculations

Ten plants were selected randomly to record the number of fully opened, green and photosynthetically active leaves. The area of the third leaf from the top was measured using a leaf-area meter and leaf area index (LAI) was calculated following Watson (1947). For dry matter accumulation, five plants were sampled; the shoot portion was collected intact, sun-dried for 24 h and subsequently oven-dried at 80 °C to constant weight. At harvest, yield attributes such as cob length, cob girth, number of rows cob⁻¹, number of grains row⁻¹ and 1000-grain weight were recorded. Harvest index was determined as the percentage of grain yield to total biological yield, following Donald (1962).

Statistical analysis

The experiment was conducted in a split-plot design with three replications. The manuscript presents the standard error of mean (SEm) and critical difference (CD) at P = 0.05 for the main treatment effects. However, the source file does not include the complete analysis of variance (ANOVA) table or statistical information on the tillage × weedmanagement interaction. Therefore, no additional conclusions regarding interaction effects were drawn or interpreted in the present revision. Since conservation-agriculture practices can influence weed populations, suitable weed-management strategies are essential to achieve better crop growth rather than depending on tillage alone [3,6] . supported early crop growth. In comparison, the performance of conservation tillage may vary depending on local climatic conditions, soil properties and effective management of crop residues [1,2] . Better dry matter accumulation under effective weed control may be attributed to reduced competition for available resources, resulting in greater assimilate production. However, the lower performance of zero tillage observed in this experiment may vary with site, climatic conditions and management practices [1,2,4] . 4). Better weed suppression likely improved resource availability during the critical reproductive stages, resulting in improved yield attributes [6,7] .

Results and Discussion

Harvest index

Tillage treatments did not significantly affect harvest index (Fig 1). However, conventional tillage recorded the highest numerical value (38.22%), followed by ZT+M (37.84%) and ZT (37.05%). Among the weed-management practices, pendimethalin recorded the highest harvest index (38.22%), followed by tembotrione and manual weeding, whereas the lowest value was observed in the weedy check (37.14%). Since only the main-effect means were reported, the response of individual tillage × weed-management combinations could not be assessed from the available data.

Overall interpretation

The experiment showed that there is a significant maineffect superiority of the conventionally ploughed treatment in terms of the studied crop-growth characteristics and several yield-related attributes for the tested rabi maize environment. Efficient weed control was additionally found to contribute significantly to increased crop growth, where pendimethalin always provided the maximum values among the four weed control measures. The treatment combination ZT+M outperformed ZT in almost all measured growth and yield attribute factors, which could indicate that the residue retention strategy could have a complementary role in addition to decreased soil disturbance. However, the current dataset does not include the grain yield factor, treatment interaction means, weed density/biomass, or economic benefit. Consequently, conclusions should be restricted to the reported growth and yield attributes and harvest index.

Conclusion

Under the rabi 2020-21 conditions of the experimental site at OUAT, Bhubaneswar, conventional tillage resulted in better crop growth and recorded the highest values for most of the measured yield attributes of maize. Among the weedmanagement practices, pre-emergence application of pendimethalin at 1 kg ha⁻¹ generally recorded higher leaf number, LAI, dry matter accumulation and several yield attributes, followed by tembotrione. Zero tillage with paddystraw mulch also performed better than zero tillage with dibbling alone. These results highlight the importance of combining suitable tillage and weed-management practices. However, multi-season studies covering grain yield, weed dynamics, economics and tillage × weed-management interactions are required before recommending a suitable combination for sandy loam soils of Odisha.

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