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Current IssueEditorial BoardOnline First Articles
Agricultural Science Digest
Print ISSN: 0253-150X
Online ISSN: 0976-0547
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Rani Lakshmi Bai Central Agricultural Uni., Jhansi, U.P., INDIA
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Full Research Article

Integrating Organic Amendments with Chelated Micronutrients for Improving Finger Millet (Eleusine coracana L.) Productivity under Calcareous Soil Condition

V. Jawahar1,*, R. Mohanapriya1, K. Udhaya Kumar1, B. Balaganesh2, C. Samyuktha1
1Division of Agronomy, Karunya Institute of Technology and Sciences, Coimbatore-641 114, Tamil Nadu, India.
2Division of Soil Sciences and Agricultural Chemistry, Karunya Institute of Technology and Sciences, Coimbatore-641 114, Tamil Nadu, India.

ABSTRACT

Background: Calcareous soils, covering 1.5 billion acres globally, which is around 17% of the country’s geographical area of which India is having about 229 million hectares. Excessive NaCO3 and CaCO3 levels form water-impermeable caliche layers which limits mineralization and water retention in soil causes phosphorous fixation and ammonia volatilization. Under these condition plant experiences the iron chlorosis, poor germination and micro nutrient deficiencies. Synthetic fertilisers are avoided in calcareous soil due to nitrogen loss via volatilization and phosphorous fixation into insoluble form. To overcome these constraints addition of organic amendments along with chelated micronutrients are crucial for enhancing soil properties, nutrient uptake and crop productivity under calcareous condition.

Methods: In this context a field experiment was conducted at Karunya Institute of Technology and Sciences, Coimbatore during rabi 2023-24 to study the effect of organic amendments and foliar nutrition under calcareous soil condition. The experiment was laid out in Factorial randomised block design with three replications. The treatments comprised of different organic amendments as a soil application and chelated micronutrient as a foliar application.

Result: Results indicated that the application of Pongamia seed cake @ 1.46 t ha-1+100 % RDF + Fe-EDTA 0.2% @ 30 and 45 DAS significantly improved growth characteristics viz plant height and DMP and the physiological parameters viz, SPAD value, CGR with higher grain yield (2891 kg ha-1), straw yield (5752 kg ha-1), biological yield (8643 kg ha-1) with higher B:C ratio. The same treatment combination recorded higher crop nutrient uptake and soil available nutrients with maximum NUE.

INTRODUCTION

Finger millet contains 7.3% protein, 19.1% dietary fibre and 102 mg/100 g total phenol (Saldivar, 2003). Globally India is the largest millet producer, with a production potential of 10.91 MT in 2021-22, contributing 30-35 M ha under worldwide millet cultivation (World Atlas, 2023). In 2024, Karnataka is the leading finger millet producer with 8,65,000 tonnes, followed by Tamil Nadu 1,89,000 tons and Uttarakhand 1,01,000 tonnes (Statista, 2024). Calcareous soils cover about 1.5 billion acres globally, accounting 17% of the world’s soils. In India is around 229 million hectares, representing 69.4% of the country’s geographical area (Pal et al., 2000). High CaCO3 reduces nutrient availability, lowering phosphorus levels and causing iron, zinc and manganese deficiencies due to decreased solubility at alkaline pH. Synthetic fertilizers are avoided in calcareous soils due to nitrogen loss from ammonia volatilization and phosphorus fixation into insoluble forms. Organic amendments in calcareous soil improve pH stability, structure, porosity and water holding capacity (Zaki and Habashy, 2011), while their integration with inorganic fertilizers enhances yield and soil health; high C:N residues are less effective (Gupta and Bordoloi, 2024). Chelated micronutrient enhances nutrient uptake in calcareous soil through foliar by preventing micronutrient precipitation and plant absorption. Organic amendments outperform with inorganic fertilizers with residual benefits and combining them with chelated micronutrients boosts crop growth and yields (Taalab et al., 2019).

MATERIALS AND METHODS

The experiment was conducted at Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu (latitude is 10o56'N and the longitude is 76o45'E and 474 m MSL) during rabi 2023-24. The experiment was laid out in a factorial randomized block design consisting of five soil amendments S3-Pongamia seed cake @ 1.46 t ha-1 +100%  RDF, S2-Neem seed cake @ 1.25 t ha-1 +100 % RDF, S3 -Castor seed cake @1.45 t ha-1 +100 % RDF, S4- FYM @ 12.5 t ha-1 +100 % RDF, S5 -100 % RDF alone (Control) and four foliar nutrition viz., F1 -Fe-EDTA 0.2% @ 30 and 45 DAS, F2-Zn-EDTA 0.5 % @ 30 and 45 DAS, F3-Mn-EDTA 0.5% @ 30 and 45 DAS, F4- No spray (Control). The statistical analysis was performed using AGRES software at a 5% significance level of significance.
       
Growth parameters were recorded periodically at 30, 60 DAS and at harvest while yield was measured at harvest. Physiological parameters were determined using the following procedures.
 
Crop growth rate
 
CGR was determined using the formula proposed by Watson (1958) and is expressed in g m-2 day-1.


W1 and W2 = Plant dry weight (g) at time t1 and t2 respectively.
(T2 - T1)   = Time interval (days).
P = Spacing occupied by the plant (m2).
 
SPAD value
 
The greenness of the leaves was measured using a SPAD 502 Plus chlorophyll meter between 11 AM and 12 PM.
 
Nutrient use efficiency
 
Agronomic use efficiency (AUE)
 
AUE measures the increase in crop yield per unit of nutrient applied, indicating the effectiveness of applied nutrients in improving crop productivity (Donald, 1963).

 
Recovery use efficiency (RUE)
 
RUE reflects the proportion of applied nutrients that are taken up by the plant, indicating nutrient uptake efficiency (Dobermann, 2005).


Biological use efficiency (BUE)
 
BUE quantifies the biomass or yield produced per unit of nutrient taken up by the crop, reflecting nutrient utilization efficiency (Moll et al., 1982):

 
Economic use efficiency (EUE)
 
EUE measures the economic return per rupees of nutrient applied, highlighting the profitability of nutrient inputs (Timsina, 2021).

 
Chemical analysis
 
The physico-chemical characteristics of initial and final soil samples were estimated as per the standard procedures and the values are presented in Table 1. To estimate nutrient uptake, the plant samples were collected at harvest, oven-dried at 65±5oC and powdered by using willey mill. N was estimated using Micro kjeldhal method given by Humphries (1956), P using colorimetric method (Jackson,1973) and K by flame photometric method (Jackson,1973). The nutrient uptake was computed using the following formula:


Table 1: Physico-chemical characteristics of initial soil.

        
The micronutrient content of plant samples at harvest was estimated using an atomic absorption spectro photometer and the nutrient uptake was computed using the formula (Lindsay and Norvell, 1978):

 
Economics
 
For each treatment, the total cost of cultivation, including all expenses was calculated and expressed in ₹ ha-1.
 
Gross returns (₹ha-1) = Monetary value of the grain (₹kg-1) + straw (₹kg-1)
 
Net returns (₹ha-1) = Gross return (₹ha-1) -Total cost of cultivation (₹ha-1)

  
Partial budgeting (₹ha-1) = (added income or reduced cost) - (increased or reduced income).

RESULTS AND DISCUSSION

Growth analysis
 
The impact of soil amendments with micronutrients on growth and physiological parameters of finger millet was depicted in Fig 1 and 2. Pongamia seed cake @ 1.46 t ha-1 + 100% RDF recorded highest plant height (108 cm), DMP (6,457 kg ha-1), SPAD (25.8) and CGR (4.5 g m-2 day-1)  followed by neem seed cake @ 1.25 t ha-1 + 100% RDF. Adequate nitrogen supply promoted cell division and multiplication, leading to an increase in plant height due to enhanced growth and development. The slow nitrogen release over time steadily increased DMP reported by Osman et al. (2009) and Biswas et al. (2023). The lowest values of plant height (88 cm), DMP (4,967 kg ha-1), SPAD (24.08) and CGR (3.017 g m-2 day-1) were observed in 100% RDF alone. Among foliar nutrition, Fe-EDTA 0.2% @ 30 and 45 DAS recorded highest plant height (104 cm), DMP (6049 kg ha-1), SPAD (27.31) and CGR (4.16 g m-2 day-1) followed by Zn-EDTA 0.5% @ 30 and 45 DAS. Application of Fe-EDTA boosts SPAD value by providing readily absorbed Fe²+, crucial for chlorophyll synthesis and preventing oxidation of Fe³+ to Fe² and thus improve chlorophyll content. The results are in line with Akhtar et al. (2019). The lowest values of plant height (93 cm), DMP (5171 kg ha-¹), SPAD value (24.04) and CGR (3.36 g m-2 day-1) were observed in control (no spray) this is due to lack of organic amendments and micronutrients reduced nutrient availability, impairing photosynthesis and transpiration, thus limiting plant growth (Ramzani et al., 2016).

Fig 1: Effect of organic amendments and foliar nutrition on plant height(cm) and DMP (kg ha-1).



Fig 2: Effect of organic amendments and foliar nutrition on SPAD value and CGR (g m-2 day-1).


 
Grain and straw yield
 
The data on grain and straw yield are presented in Table 2. Pongamia seed cake @ 1.46 t ha-1 +100% RDF recorded the highest grain yield (2891 kg ha-1), straw yield (5752 kg ha-1) and biological yield of 8643 kg ha-1, which was statistically comparable with neem seed cake @ 1.25 t ha-1 +100% RDF. While significantly lower grain yield (1239 kg ha-1), straw yield (4203 kg ha-1) and biological yield (5442 kg ha-1) were observed in 100% RDF alone. Nitrification inhibitors reduce nitrogen loss, enabling slow release, better absorption, improved photosynthesis, higher dry matter and yield. The results confirm with Chitte et al. (2016) and Biswas et al. (2023). Among foliar nutrition Fe-EDTA 0.2% @ 30 and 45 DAS recorded highest grain yield (2724 kg ha-1), straw yield (5367 kg ha-1) and biological yield (8091 kg ha-1), which were statistically on par with Zn-EDTA 0.5%. Foliar feeding enhances cell division, physiological processes and timely nutrient supply, thereby improving yield parameters (Chitte et al., 2016). Whereas, lowest grain yield (2188 kg ha-1), straw yield (4695 kg ha-1) and biological yield (6883 kg ha-1) was recorded in control.

Table 2: Effect of organic amendments and foliar nutrition on grain yield, straw yield and biological yield of finger millet.


 
Nutrient uptake by plant
 
Values on plant uptake at harvest were presented in Table 3 shows Pongamia seed cake @ 1.46 t ha-1 + 100% RDF recorded the highest N (116 kg ha-1), P (22 kg ha-1), K (59 kg ha-1), Fe (2,354 g ha-1), Zn (366 g ha-1) and Mn uptake (144 g ha-1) followed by neem seed cake @ 1.25 t ha-1 + 100% RDF. This might be attributed directly to the ammonium, readily absorbed by roots, boosts nitrogen uptake and assimilation when nitrification is inhibited (Majumdar, 2008). Similar findings were reported by Biswas et al. (2023). Application of organic amendments improving NPK uptake and seed nutrition were noted by Haiguipeung et al. (2025).        

Table 3: Effect of organic amendments and foliar nutrition on plant nutrient uptake at harvest of finger millet.



Whereas, the lower soil available nutrients were recorded in 100% RDF alone. Comparing various foliar nutrition, the higher N (116 kg ha-1), P (21 kg ha-1), K (55 kg ha-1), Fe (2,216 g ha-1), Zn (312 g ha-1) and Mn uptake (138 g ha-1) was observed under Fe-EDTA 0.2% @ 30 and 45 DAS. Fe-EDTA 0.2% @ 30 and 45 DAS than control. Foliar Fe-EDTA application bypasses soil limitations, reduces Zn antagonism and enhances Fe uptake and utilization. Fe-EDTA improves its availability for physiological functions, indirectly boosting Zn assimilation, yield and grain micronutrient content (Ram et al., 2014).
 
Soil available nutrients
 
Table 4 shows the influence of soil amendments and foliar treatment on post-harvest nutrient status. Pongamia seed cake @ 1.46 t ha-1 + 100% RDF recorded highest soil available N (188 kg ha-1), P (20 kg ha-1), K (280 kg ha-1), Fe (4.33 mg kg-1), Zn (1.78 mg kg-1) and Mn (14.36 mg kg-1) followed by neem seed cake @ 1.25 t ha-1 + 100% RDF and lower N (146 kg ha-1), P (14 kg ha-1), K (233 kg ha-1), Fe (3.15 mg kg-1), Zn (1.11 mg kg-1) and Mn (12.12 mg kg-1) were estimated in 100% RDF alone. It seems to be due to the nitrification inhibitors slow down the conversion of ammonium (NH4+) to nitrate (NO3-) which enhancing ammonium persistence in soil (Majumdar, 2008). Organic amendments stabilize soil pH through microbially produced enzymes, thereby enhancing available NPK in the soil were reported by Kumar et al. (2023). This reduces nitrogen losses, improving nitrogen availability in soil. The control had lower levels of Fe and Zn because it lacked nutrient amendments, which were necessary to enhance nutrient bioavailability and uptake by plants reported by Ramzani et al. (2016) and Gowda et al. (2004). In foliar nutrition, Fe-EDTA 0.2% @ 30 and 45 DAS resulted in the highest soil available N (177 kg ha-1), P (19 kg ha-1), K (270 kg ha-1), Fe (3.97 mg kg-1), Zn (1.68 mg kg-1) and Mn (13.80 mg kg-1). The retention of Fe in soil by foliar Fe-EDTA is linked to adsorption by inorganic colloids (oxides, hydroxides, carbonates, phosphates) and organic colloids (Bhatti et al., 2024). Whereas, the lower soil available nutrients were recorded in control.

Table 4: Effect of organic amendments and foliar nutrition on soil available nutrients.


 
Nutrient use efficiency
 
The impact of amendments and micronutrient on NUE were presented in Table 5. Pongamia seed cake @ 1.46 t ha-1 + 100% RDF + Fe-EDTA 0.2% @ 30 and 45 DAS showed the higher AUE for NPK (11.73, 11.2 and 33.0%) over control. Nitrification inhibitors regulate nitrogen release, ensuring sustained nutrient availability throughout the cropping season which increased nutrient uptake, enhanced yield attributes, yield and improved NUE for crops (Chitte et al., 2016). The highest RUE was recorded for N (0.85) in FYM @ 12.5 t ha-1+ Zn-EDTA 0.5% @ 30 and 45 DAS and for P (1.95) and K (0.67) in FYM @ 12.5 t ha-1 + no spray. It is due to the variable rate of nutrient uptake by finger millet under calcareous soil condition. Pongamia seed cake @ 1.46 t ha-1 +100% RDF+ Fe-EDTA 0.2% @ 30 and 45 DAS recorded the highest BUE for NPK was 17.81, 17.0 and 49.8 %, as well as the highest EUE for NPK was 95.8, 58.4 and 75.0 % over 100% RDF alone + no spray.

Table 5: Effect of organic amendments and foliar nutrition on nutrient use efficiency of finger millet.


 
Economics
 
The economic returns and partial budgeting were furnished in Table 6. Pongamia seed cake @ 1.46 t ha-1 + 100 % RDF + Fe-EDTA 0.2% @ 30 and 45 DAS, which achieved highest net return (₹ 80,444 ha-1), B:C ratio (2.64) and net gain (₹ 61,394 ha-1) with the cost of cultivation of ₹ 48,945. Similar findings stated by Osman et al. (2009). The lower net return (₹ 27,753 ha-1) and B:C ratio (1.43) was recorded under FYM @ 12.5 t ha-1 +100% RDF + no spray. The net loss of  ₹ 151 ha-1 was observed in 100% RDF Alone + Mn-EDTA 0.5% @ 30 and 45 DAS. 

Table 6: Effect of organic amendments and foliar nutrition on economics and partial budgeting of finger millet.

CONCLUSION

The study found that combining organic amendments with chelated micronutrients registered significantly increased growth components, physiological parameters, yield and economics at harvest. It also improved crop nutrient uptake, post-harvest soil available nutrients with higher nutrient use efficiency in finger millet. Hence it is concluded that application of Pongamia seed cake @ 1.46 t ha-1 +100% RDF+ Fe-EDTA 0.2% @ 30 and 45 DAS highlighting the essential role of proper nutrient management for improving finger millet productivity and soil fertility under calcareous soil condition.

CONFLICT OF INTEREST

All authors declared that there is no conflict of interest.

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