Influence of split nitrogen application on nutrient uptake, quality and soil fertility in summer pearl millet

Introduction

Pearl millet (Pennisetum glaucum L.) is an important cereal crop cultivated extensively in arid and semi-arid regions of India for food, feed and fodder purposes. The crop is well known for its adaptability to drought, high temperature and poor soil fertility conditions. Because of its hardy nature and efficient utilization of soil moisture, pearl millet has become an indispensable component of dryland and irrigated cropping systems in many parts of the country. Besides its agronomic importance, pearl millet grains possess high nutritional value with appreciable amounts of protein, carbohydrates, minerals and dietary fibre, making it an important crop for nutritional security. In recent years, cultivation of summer pearl millet has gained momentum in Gujarat due to the availability of irrigation facilities and adoption of intensive cropping systems. Summer cultivation offers several advantages such as higher solar radiation, better resource utilization, lower pest and disease incidence and stable productivity. Consequently, pearl millet has emerged as an economically viable crop in sequences like cotton-summer pearl millet, potato-summer pearl millet and tobacco-summer pearl millet. However, sustaining higher productivity and maintaining soil fertility under intensive cultivation largely depend upon balanced and efficient nutrient management practices. Among the essential nutrients, nitrogen plays a pivotal role in crop growth, development and quality improvement.

Nitrogen is an integral constituent of chlorophyll, amino acids, proteins, nucleic acids and several enzymes involved in metabolic activities of plants. Adequate nitrogen nutrition promotes vigorous vegetative growth, enhances photosynthetic activity and improves nutrient accumulation in plant tissues. Nitrogen also directly influences protein synthesis and thereby improves the nutritional quality of pearl millet grain and fodder. However, deficiency of nitrogen results in poor crop growth, reduced nutrient uptake and lower yield and quality. Nitrogen use efficiency in pearl millet is often low because of substantial losses through leaching, volatilization and denitrification, especially in sandy and sandy loam soils of North Gujarat. Application of excessive nitrogen at a single time may not only reduce nutrient use efficiency but may also lead to environmental problems and deterioration of soil health. Therefore, split application of nitrogen according to crop demand at different growth stages is considered an effective approach for improving nutrient availability, enhancing uptake efficiency and minimizing nutrient losses. Split nitrogen application helps synchronize nutrient supply with crop requirement and forms an important component of efficient nutrient management practices. Several researchers have reported beneficial effects of split nitrogen application on nutrient content, nutrient uptake, protein content and quality parameters of pearl millet and other cereal crops. Proper scheduling of nitrogen not only improves crop productivity but also influences residual soil fertility status after harvest. Maintenance of soil nutrient balance is essential for sustaining crop productivity under intensive cropping systems. Nevertheless, information regarding the effect of different nitrogen split schedules on nutrient uptake, quality and soil fertility status of summer pearl millet under North Gujarat conditions is limited. Considering these aspects, the present investigation entitled "Influence of Split Nitrogen Application on Quality, Nutrient Uptake and Soil Fertility of Summer Pearl millet (Pennisetum glaucum L.)" was undertaken to study the effect of different nitrogen split applications on quality parameters, nitrogen content and uptake, and post-harvest soil fertility status of summer pearl millet under North Gujarat conditions.

Materials and Methods

A field experiment entitled "Influence of Split Nitrogen Application on Quality, Nutrient Uptake and Soil Fertility of Summer Pearl millet (Pennisetum glaucum L.)" was conducted during the summer season of 2024 at the Agronomy Instructional Farm, Chimanbhai Patel College of Agriculture, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar, Gujarat. The experimental site is geographically located at 24°19′ North latitude and 72°19′ East longitude with an elevation of 154.52 m above mean sea level and falls under the North Gujarat Agroclimatic Zone. The region experiences a semi-arid and subtropical climate characterized by hot summers and mild winters. The weather conditions during the crop season remained favourable for satisfactory crop growth and no rainfall was received during the experimental period. Prior to initiation of the experiment, composite soil samples were collected from 0-15 cm depth and analyzed for physicochemical properties. The experimental soil was loamy sand in texture, low in organic carbon (0.28%) and available nitrogen (164.71 kg ha⁻¹), medium in available phosphorus (31.79 kg P₂O₅ ha⁻¹) and high in available potassium (273.37 kg K₂O ha⁻¹). The soil was slightly alkaline in reaction with pH 7.51 and EC 0.12 dS m⁻¹. The experiment was laid out in a Randomized Block Design (RBD) with seven treatments replicated four times. Pearl millet hybrid GHB 1129 was used as the test crop. The gross plot size was 6.0 m × 3.6 m and net plot size was 4.5 m × 2.7 m with row spacing of 45 cm. The crop was sown manually on 6 March 2024 using a seed rate of 3.75 kg ha⁻¹. The treatments consisted of different schedules of split nitrogen application viz., T₁: 100% recommended dose of nitrogen (RDN) applied as 50% basal + 50% at tillering, T₂: 100% RDN applied as 25% basal + 37.5% at tillering + 37.5% at earhead emergence, T₃: 100% RDN applied as 25% basal + 25% at tillering + 50% at earhead emergence, T₄: 100% RDN applied as 25% basal + 25% at tillering + 25% at earhead emergence + 25% at flowering, T₅: 75% RDN applied as 50% basal + 50% at tillering, T₆: 75% RDN applied as 25% basal + 25% at tillering + 50% at earhead emergence and T₇: 75% RDN applied as 25% basal + 25% at tillering + 25% at earhead emergence + 25% at flowering. Nitrogen was applied through urea as per treatment schedule, while phosphorus @ 60 kg P₂O₅ ha⁻¹ was applied uniformly as basal through single super phosphate to all treatments. The experimental field was prepared by ploughing followed by harrowing and planking to obtain proper tilth. Irrigations were applied uniformly to all treatments according to crop requirement and soil moisture condition. Recommended agronomic practices including thinning, hand weeding and inter culturing were followed throughout the crop growth period. The crop was harvested at physiological maturity and produce from each net plot was separately threshed, cleaned and recorded. For quality analysis, representative grain samples collected from each treatment were analyzed for nitrogen content by Micro-Kjeldahl's method as described by Jackson (1973). Protein content in grain was calculated by multiplying nitrogen content with a factor of 6.25. Protein yield was worked out by multiplying protein content with grain yield. Nitrogen uptake by grain and straw was calculated by multiplying nitrogen content (%) with corresponding grain and straw yield. Post-harvest soil samples were collected from each plot at 0-15 cm depth and analyzed for available nitrogen, phosphorus and potassium using standard analytical procedures. Available nitrogen was estimated by alkaline permanganate method, available phosphorus by Olsen's method and available potassium by flame photometric method. The experimental data obtained for quality parameters, nutrient content, nutrient uptake and soil fertility status were statistically analyzed using analysis of variance technique appropriate to Randomized Block Design as suggested by Panse and Sukhatme (1967). The significance of treatment differences was tested by 'F' test and critical difference (CD) at 5% level of significance was used for comparison of treatment means.

References

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