Effect of seed treatment with biofertilizer and NPK application on soil health of chickpea (Cicer arietinum L.)

Introduction

Chickpea (Cicer arietinum L.) is one of the most important pulse crops belonging to the family Fabaceae and is widely cultivated for its nutritional value and soil fertility improvement. It is a rich source of protein, carbohydrates, vitamins, minerals and dietary fibre making it an important component of human diet, particularly in vegetarian populations (Ali et al.,2018) [1] . India is the largest producer and consumer of chickpea in the world, where the crop is mainly cultivated during the rabi season under both irrigated and rainfed conditions (FAO, 2023) [5] . Chickpea has the unique ability to fix atmospheric nitrogen through symbiotic association with Rhizobium bacteria, which improves soil fertility and reduces the requirement of chemical nitrogen fertilizers (Singh et al., 2017) [19] . Balanced application of nitrogen, phosphorus, and potassium fertilizers significantly enhances plant growth, nodulation, flowering, and grain yield in chickpea (Sharma et al., 2020) [13] . Studies has further revealed that integrated nutrient management involving chemical fertilizers along with biofertilizers such as Rhizobium and phosphate-solubilizing bacteria improves nutrient uptake, soil health, and overall productivity of chickpea (Kumar et al., 2019) [8] . Inoculation with biofertilizers also increases biological nitrogen fixation and phosphorus availability, resulting in higher seed yield and better economic returns (Patel et al., 2021) [11] .

Materials and methods

The present study entitled "Effect of Seed Treatment with Biofertilizer and NPK application on Soil health of Chickpea (Cicer arietinum L.)" Varity PUSA-362 comprise of a field experiment which was carried out at the Soil Science and Agricultural Chemistry Research Farm Prof. Rajendra Singh (Rajju Bhaiya) University Naini Prayagraj during Rabi season 2025-2026. The maximum temperature of the location reaches up to 46 °C-48 °C and seldom falls as 4 ^ 0C-5 ^ 0 C. The relative humidity ranged between 20 to 94%. The average rainfall in this area is around 1100 mm annually. It comes under subtropical climate receiving the mean annual rainfall of about 1100 mm, major rainfall from July to end of September. However, occasional precipitation was also not uncommon during winter. The winter months were cold while summer months were very hot and dry. The minimum temperature during the crop season was to be 5.4 ⁰C and the maximum is to be 41.2 ⁰C. The minimum humidity was 48.2% and maximum was to be 87.6%. Experiment was laid out in randomized block design with Different level of NPK and bio fertilizer with seed treatment. Plot size was 3x3m² for crop seed rate is 60-80 kg ha-1 (Cicer arietinum L.) Var PUSA-362. Basal dose of fertilizer was applied in respective plots according to treatment allocation uniform furrows opened by about 5 cm. All the agronomic practices were carried out uniformly to raise the crop. The crop was harvested in March. Treatment combination for T₁-(Absolute control), T2-(NPK @ 50%), T3-(NPK @ 100%), T4-(Rhizobium @ 20 g), T5-(PSB @ 20 g), T6-(Rhizobium @ 20 g + NPK @ 50%), T7-(PSB @ 20 δg+NPK @ 50%), T8 -(PSB @ 20 g + NPK @ 100%), T9 -(Rhizobium @ 20 g + NPK @ 100%). Bulk density, Particle density, Pore space and Water holding capacity analyze Measuring cylinder method given by Muthuvel et al.,1992

The data presented in table and fig. 1 clearly shows the bulk density (Mgm⁻³) of soil as influenced by seed treatment with biofertilizer and NPK sources of nutrients. The maximum bulk density of soil was recorded 1.29 and 1.38 Mg m-3 at 0-15 and 15-30 cm in treatment T₁ (Absolute control) followed by 1.27 and 1.28 Mg m⁻³ at 0-15 and 15-30 cm in treatment T₂ (NPK @ 50%) and minimum bulk density of soil was recorded 1.12 and 1.21 Mgm⁻³ at 0-15 and 15-30 cm in treatment T₉ (Rhizobium @ 20 g Seed treatment + NPK @ 100%) respectively. However, this difference was statistically Non-Significant (NS) at both soil depths. Naturally, bulk density depends on soil texture and does not change in a single crop season. To make a big change in bulk density, we need to add large amounts of organic manure for many years. Since this was a short-term experiment, the fertilizers and biofertilizers did not change the soil weight and volume ratio significantly. Similar result has been recorded by.

The data presented in table and fig. 1 clearly shows the particle density (Mgm⁻³) of soil as influenced by organic and inorganic source of nutrients. The maximum particle density of soil was recorded 2.53 and 2.57 Mg m⁻³ at 0-15 and 15-30 cm in treatment T₁ (Absolute control) followed by 2.50 and 2.63 Mg m-3 at 0-15 and 15-30 cm in treatment T₂ (NPK@50%) and minimum particle density of soil was recorded 2.29 and 2.34 Mg m⁻³ at 0-15 and 15-30 cm in treatment T₉ (Rhizobium @ 20 g Seed Treatment + NPK @ 100%) respectively. This small change was completely non-significant. Particle density only measures the weight of the solid soil particles, without counting any air or water spaces. Because the mineral composition of any field soil is fixed and permanent, adding chemical fertilizers or biofertilizer seed treatments cannot change the weight of the solid minerals, leading to a non-significant result. Similar result has been recorded by (Gulaiya et al., 2023 and Patel et al., 2024 and Begum et al., 2022.) [6,10] Pore space (%) The data presented in table and fig. 1 clearly shows the pore space (%) of soil as influenced by seed treatment with biofertilizer and NPK source of nutrients. The maximum pore space of soil was recorded 54.78 and 52.15% at 0-15 and 15-30 cm in treatment T₉ (Rhizobium @ 20 g Seed Treatment + NPK @ 100%) followed by 53.27 and 51.20% at 0-15 and 15-30 cm in treatment T₈ (PSB @ 20 g Seed Treatment +NPK @ 100%) and minimum pore space of soil was recorded 48.50 and 46.53% at 0-15 and 15-30 cm in treatment T₁ (Absolute control) respectively. This positive change happened because 100% NPK and Rhizobium together helped the chickpea plant grow better roots. The growing roots pushed the soil particles and created small channels. When the roots decayed after harvest, they left behind empty spaces, which significantly increased soil porosity. Similar result has been recorded by (Gulaiya et [6,10]

The data presented in table and Fig. 1 clearly shows the water holding capacity (%) of soil as influenced by seed treatment with biofertilizer and NPK source of nutrients. The maximum water holding capacity of soil was recorded 42.53 and 40.51% at 0-15 and 15-30 cm in treatment T₉ (Rhizobium @ 20 g Seed Treatment + NPK @ 100%) followed by 42.43 and 40.25% at 0-15 and 15-30 cm in treatment T₈ (PSB @ 20 g Seed Treatment +NPK @ 100%) and minimum water holding capacity of soil was recorded 39.36 and 36.73% at 0-15 and 15-30 cm in treatment T₁ (Absolute control) respectively. This significant increase happened because better root growth and bacteria released natural sticky substances that bound soil particles together. This improved the soil structure and increased the number of small capillary pores, which are responsible for holding water against gravity. Similar result has been recorded by (Gulaiya et al., 2023 and Patel et al.,2024 and Begum et al., 2022.) [6,10]

5) w/v

The data presented in table and fig. 2 clearly shows the pH of soil as influenced by seed treatment with biofertilizer and NPK source of nutrients. The maximum pH of soil was recorded 7.34 and 7.39 at 0-15 and 15-30 cm in treatment T1 (Absolute control) followed 7.11 and 7.38 at 0-15 and 15-30 cm in treatment T₂ (NPK @ 50%) and minimum pH of soil was recorded 6.29 and 6.51 at 0-15 and 15-30 cm in treatment T₉ (Rhizobium @ 20 g Seed Treatment + NPK @ 100%)) respectively. This significant reduction is caused by root and microbial activities. The Rhizobium bacteria in root nodules breathe actively while fixing nitrogen, releasing carbon dioxide (CO2) gas. This gas reacts with soil moisture to form weak carbonic acid. Also, roots release hydrogen ions (H+) during nutrient uptake, which lowers the Soil pH. Similar result has been recorded by (Datta et al., 2008.) [4] Soil EC (dSm-1)

The data presented in table and fig. 2 clearly shows the EC of soil as influenced by seed treatment with biofertilizer and NPK source of nutrients. The maximum EC of soil was recorded 0.46 and 0.48 dSm-1 at 0-15 and 15-30 cm in treatment T₉ (Rhizobium @ 20 g Seed Treatment + NPK @ 100%) followed by 0.44 and 0.46 dSm-1 at 0-15 and 15-30 cm in treatment T₈ (PSB @ 20 g Seed treatment +NPK @100%) and minimum EC of soil was recorded 0.31 and 0.32 dSm-1 at 0-15 and 15-30 cm in treatment T₁ (Absolute control) respectively. the statistical test proved this was non-Significant. Soil EC shows the amount of soluble salts in the soil water. Adding 100% chemical NPK fertilizers added some salts, which is why the numbers look higher. However, the growing chickpea plants quickly absorbed these nutrients. Also, irrigation or rain washed some salts down into deeper soil layers, preventing any significant salt accumulation in the topsoil. Similar result has been recorded by (Gulaiya et al., 2023 and Patel et al., 2024 and Begum et al., 2022.) [6,10] Organic carbon (%)

The data presented in table and fig. 2 clearly shows the organic carbon (%) of soil as influenced by seed treatment with biofertilizer and NPK source of nutrients. The maximum organic carbon of soil was recorded 0.46 and 0.48% at 0-15 and 15-30 cm in treatment T₉ (Rhizobium @ 20gram Seed treatment +NPK @ 100%) followed by 0.44 and 0.46% at 0-15 and 15-30 cm in treatment T₈ (PSB @ 20gram Seed Treatment +NPK @ 100%) and minimum organic carbon of soil was recorded 0.31 and 0.32% at 0-15 and 15-30 cm in treatment T₁ (Absolute control) respectively. because the top layer receives most of the organic matter, like root nodules, root exudates, and plant residues left after harvest. The lower layer (15-30 cm) has very few roots and no organic input, so the values remained non-significant. Similar result has been recorded by (Gulaiya et al., 2023 and Patel et al., 2024 and Begum et al., 2022.) [6,10]

The data presented in table and fig. 3 clearly shows the available nitrogen (kg ha-1) of soil as influenced by seed treatment with biofertilizer and NPK source of nutrients. The maximum available nitrogen of soil was recorded 304.77 and 286.39 kg ha⁻¹ at 0-15 cm and 15-30 cm in treatment T₉ (Rhizobium @ 20gram Seed Treatment + NPK @ 100%) followed by 287.52 and 264.52 kg ha-1 at 0-15 and 15-30 cm in treatment T₈ (PSB @ 20gram Seed Treatment +NPK @ 100%) and minimum available nitrogen of soil was recorded 262.60 and 241.59 kg ha⁻¹ at 0-15 and 15-30 cm in treatment T₁ (Absolute control) respectively. This significant increase is due to the combined power of chemical and biofertilizers. 100% NPK gave a fast starter supply of nitrogen to the young plants, while Rhizobium seed treatment fixed atmospheric nitrogen directly into the soil through root nodules. This left a high amount of available nitrogen in the soil after harvest. Similar result has been recorded by (Gulaiya et al., 2023 and Patel et al., 2024 and Begum et al., 2022.) [6,10] Available phosphorus (kg ha-1)

The data presented in table and fig. 3 clearly shows the available phosphorus (kg ha-1) of soil as influenced by seed treatment with biofertilizer and NPK source of nutrients. The maximum available phosphorus of soil was recorded 27.16 and 24.37 kg ha-1 at 0-15 and 15-30 cm in treatment T₈ (PSB @ 20gram Seed Treatment +NPK @ 100%) followed by 26.75 and 24.77 kg ha-1 at 0-15 and 15-30 cm in treatment T₉ (Rhizobium @ 20gram Seed Treatment + NPK @ 100%) and minimum available phosphorus of soil was recorded 23.19 and 21.02 kg ha-1 at 0-15 and 15-30 cm in treatment T1 (Absolute control) respectively. when chemical phosphorus is applied, a large part gets locked up in the soil. However, in T₈, Phosphate Solubilizing Bacteria (PSB) produced organic acids that released this fixed phosphorus. In T₉, the Rhizobium lowered the soil pH to 6.29, which naturally made the phosphorus more soluble and available. Similar result has been recorded by (Gulaiya et al., 2023 and Patel et al., 2024 and Begum et al., 2022.) [6,10] Available potassium (kg ha-1)

The data presented in table and fig. 3 clearly shows the available potassium (kg ha -1 ) of soil as influenced by seed treatment with biofertilizer and NPK source of nutrients. The maximum available potassium of soil was recorded 202.18 kg ha -1 at 0-15 cm and 197.58 kg ha -1 at 15-30 cm in treatment T 9 (Rhizobium @ 20gram Seed Treatment + NPK @ 100%) followed by 202.18 and 197.58 kg ha⁻¹ at 0-15 and 15-30 cm in treatment T₈ (PSB @ 20gram Seed Treatment +NPK @ 100%) and minimum available potassium of soil was recorded 189.15 and 185.37 kg ha⁻¹ at 0-15 and 15-30 cm in treatment T₁ (Absolute Control) respectively. The mean value of available potassium (kgha⁻¹) of soil was found significant. The primary reason for this significant increase is the direct addition of potassium fertilizer (MOP) under the 100% NPK treatment. Additionally, the strong root system developed by the combined treatment released organic acids into the soil. These root acids helped release the locked or non-exchangeable potassium from clay particles into an easily available form. Similar result has been recorded by (Gulaiya et

Conclusion

In the present investigation, it was apparent that application of NPK and Biofertilizer with seed treatment T₉ (Rhizobium @ 20 gram + NPK @ 100%) was found on physical and chemical parameters of soil such as bulk density, particle density,% pore space, water holding capacity, EC, pH, organic carbon, available N, P and K than other treatment combinations. Thus, it can be concluded that different levels of NPK and Bio fertilizer improved soil available nutrient, increased soil available nitrogen, phosphorus, potassium and electrical conductivity. However, pH of soil decreases and also among the treatments T₉ recorded the best treatment which increased the availability of nutrient and influenced on physical and chemical properties of soil as well.

Acknowledgement

AcknowledgementsThe authors are grateful to the Hon'ble Vice chancellor Prof. Rajendra Singh (Rajju bhaiya) University, Department of Soil Science and Agricultural Chemistry, Prayagraj for taking their keen interest and encouragement to carry out the research work.

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