Effect of Organic Granules on the Productivity, Quality, and Nutrient Uptake Level of Tomato and the Fertility and Microbial Population of the Soil

Organic vegetable production is needed worldwide to minimize the use of inorganic fertilizers, protect the environment, and produce healthy food. Accordingly, in the present study, the effects of organic granules on the productivity, quality, and nutrient uptake level of tomatoes and the fertility and microbial population of the soil were determined. Briefly, organic NPK granules and organic N, P and K-rich sources were compared with synthetic NPK granules and synthetic fertilizers administered at 100 and 75% of the recommended fertilizer levels. Among the various treatments applied, treatment with 100% of the recommended NPK using the synthetic NPK granules (Urea, DAP and MOP) led to higher growth, yield attributes, and yield (fruit yield, - 24.21 t/ha and stover yield, -15.01 t/ha) of tomato. This treatment also enhanced the nutrient uptake by tomato. However, quality parameters, such as total soluble solids (6.64% ), titrable acidity (0.62% ), ascorbic acid content (14.31 mg/100 g), lycopene content (3.54 mg/100 g), reducing sugars (3.11%), non-reducing sugars (1.02%), total sugar (4.13% ), and shelf life (15.76 days ) of tomato were higher with 100% of the recommended NPK from organic NPK granules than from synthetic granules. This treatment also enhanced the available nutrients and microbial population in the soil. Notably, the same trend was observed for tomatoes fertilized with 75 % of the recommended NPK. The lowest values were obtained with the absolute control. Based on the results of this experiment, the application of 100% of the recommended NPK using organic NPK granules is the best approach to improve the quality of tomato fruits and to enhance the soil fertility.


INTRODUCTION
Tomatoes are important vegetable crops grown worldwide and consumed in salads.Tomatoes are also processed and used to prepare sauces, ketch-ups and pickles, which contain very high amounts of vitamins A, B complex, C, and sugars.Tomatoes are nutritionally superior and less expensive than other vegetables.Globally, tomato occupies 50,51,983 hectares of area and produce 187 million tons of fruits, with an average productivity of 37.10 t/ha. 1 In India, tomato is widely grown on plains in an area of 8.40 lakh hectares with an annual production level of 20.33 mt and average productivity of 24.20 t/ha. 2 The demand for tomatoes is increasing daily owing to the growing population in India.To meet future demands, inorganic fertilizers are widely used to enhance tomato productivity.Although inorganic fertilizers significantly improves crop production, their continuous use depletes the organic matter in the soil, disrupt its physical, chemical, and biological properties, 3 and reduces its health.More than 50% of the nitrogen and 90% of the phosphorus delivered using chemical fertilizers are generally lost to the atmosphere or water sources, 4 causing the emission of greenhouse gases, water eutrophication, and other environmental pollution. 5The excessive use of chemical fertilizers decreases the yield of crops and lowers the quality of vegetables. 6As a result, people are getting increasingly concerned about environmental hazards, particularly health hazards, created by the indiscriminate use of agrochemicals. 7In many countries, organic farming has become cropping system that minimizes the use of chemicals and protects the environment and foods. 8India is a major producer and consumer of vegetables.Recently, organic farming garnered the attention of Indian farmers to enable high-quality vegetable production.Farmers use different types of organic manures, such as cow dung, goat manure, poultry manure, farmyard manure, compost, vermicompost, and oil cakes for vegetables production.Farmyard manure, vermicompost, and oil cakes are commonly used as sources of plant nutrients.These organic manures are eco-friendly, supplying essential plant nutrients to the crops including many vitamins and growth promoting substances.They also improve the soil fertility, soil microbial population, water holding capacity, and crop quality.However, the low availability of organic manure throughout the year and high transportation costs limit organic vegetable production.Further, handling and storage of these organic manures are expensive.These manures produce an undesirable odor that is inhaled by humans, and their storage is considered unhygienic as they are often stored in nearby households.Therefore, customized organic granules that are more similar to inorganic fertilizers and possess a relatively higher nutrient content than conventional organic manures are needed.These organic granules generally contain oil cakes, fish/bone meals, compost, well-rotted manure, or plant or animal residues, and provide numerous benefits to the soil ecosystem.One key advantage of organic granules is their ability to improve the soil structure.As these granules break down, they enhance soil aggregation, and promote better aeration and water drainage, inducing a healthy root environment for plants, and fostering robust growth and development.The slow-release of nutrients from the organic granules is another significant attribute.Unlike synthetic fertilizers, which induce nutrient runoff and environmental damage, organic granules gradually release nutrients.Such release ensures a sustained supply of essential elements to the plants over an extended period, thereby reducing the risk of nutrient imbalance.Furthermore, organic granules contribute to the development of rich, humus-filled soil.The organic matter in these granules serves as a food source for beneficial microorganisms, thereby promoting thriving soil microbial communities.Microbial activity enhances nutrient cycling and availability, creating a dynamic fertile soil ecosystem.In addition to enhancing soil fertility, the use of these granules aligns with environmentally friendly conscious agricultural practices.Organic materials in these granules are often recycled from waste products, thereby reducing the environmental impacts associated with conventional farming practices.By using organic granules, farmers and gardeners can contribute to biodiversity conservation and the overall health of the ecosystem. 9rganic granules slowly release nutrients into the crop; however, this release is faster than that exhibited by conventional organic manures.
The nutrient release rate of organic granules is dependent on the moisture status of the soil.Organic granules supply nutrients to crops and add organic carbon to the soil, thereby elevating yield, improving the quality of produce, and promoting a more sustainable and resilient agricultural system.Hence, in the present study, newly developed organic granules were tested to determine the productivity, quality, and nutrient uptake level of tomatoes, and the fertility and microbial populations of the soil.

Growth and yield
As shown in Tables 1 and 2, the application of organic granules significantly influenced the growth and yield of tomatoes.The tallest plant (127.01 cm), highest branch number (18.15), and highest increase in dry matter production (16.44 t/ha) were obtained when 100% of the recommended NPK was applied using synthetic NPK granules (Urea, DAP, and MOP).This treatment also led to the highest number of fruits/plant (49.20), highest single fruit weight (102.01 g), and highest increase in fruit diameter (5.76 cm) for tomato.These values may be ascribed to the supply of plant nutrients that are readily available at critical stages, ultimately enabling enhanced uptake of nutrients, increased plant metabolic activities, and improved photosynthesis.Such attributes may have led to the highest growth components and yield-attributing elements in tomatoes fertilized with this treatment.Similar results were reported by Adekiya et al., 20 who reported that the increased growth and yield of tomatoes were attributed to increased nutrient content in the soil and absorption of available nutrients by plants.These attributes significantly boosted the growth and yield-attributing characteristics of tomatoes, ultimately resulting in a higher yield.The highest values for fruit yield (24.21 t/ha) and stover yield (15.01 t/ha) were also obtained with the application of 100% of the recommended NPK using the synthetic NPK granules (Urea, DAP, and MOP).In   -Actinomycetes; N fruits -N uptake by fruits, N stover -N uptake by stover, P fruits -P uptake by fruits, P stover -P uptake by stover, K fruits -K uptake by fruits, K stover -K uptake by stover, Avail N -Available Nitrogen, Avail P -Available Phosphorus, Avail K -Available Potassium; ** Significance at 1 per cent level; * Significance at 5 per cent level; NS -Non -significant fact, the maximum number of fruits/plants and increased single fruit weight were recorded, which resulted in a higher fruit yield.The application of 100% of the recommended NPK using synthetic fertilizers led to the second highest values for the above attributes.
The application of 100% of the recommended NPK using organic NPK granules led to the third highest values, including a plant height of 117.69 cm, number of branches plant -1 of 17.24, and dry matter production of 15.21 t/ha.Owing to this treatment, the number of fruits/plant, single fruit weight, and fruit diameter of tomatoes were 45.11, 92.69 g, and 5.29 cm, respectively.The application of 100% of the recommended NPK using organic N-, P-, and K-rich sources led to the fourth highest values for the above attributes.This result may have been due to the slow and steady release of nutrients during their decomposition.Such pace ensures a continuous supply of essential elements, promotes robust vegetative growth, and supports the energy-demand of flowering and fruiting in tomato plants.Adequate nutrient availability and a well-structured soil contribute to healthier flowering and fruit setting in tomato plants.Such finding agrees with those of Melero et al. 21and Thomas et al. 22 The same trends were observed in crops fertilized with 75% of the recommended NPK.The low values for the growth and yield (fruit yield -6.13 t/ha and stover yield -7.69 t/ha) of tomatoes were obtained with the absolute control as the supply of essential nutrients was inadequate.Similar findings were reported by Melero et al. 21and Muchanga et al. 23 Soil available N (r=0.877*and 0.864**), P (r=0.889** and 0.874**), and K (r=0.883** and 0.864**) were significantly and positively correlated with the fruit and stover yield of tomatoes, there by supporting the findings of this study (Table 3).

Quality parameters
Organic granules were found to significantly influence tomato fruit quality (Tables 2 and 4).The highest total soluble solids (6.64%), titrable acidity (0.62%), ascorbic acid content (14.31 mg/100 g), lycopene content (3.54 mg/100 g), reducing sugars (3.11%), non-reducing sugars (1.02%), total sugar (4.13%), and shelf life (15.76days) were obtained with the application of 100% of the recommended NPK using organic NPK granules; this was closely followed by the addition of 100% of the recommended NPK using organic N-, P-, and K-rich sources.The following results were obtained: total soluble solids, 6.55%; titrable acidity, 0.59%; ascorbic acid content, 14.08 mg/100 g; lycopene content, 3.51 mg/100 g; reducing sugars, 3.09%; non-reducing sugars, 1.01%; total sugar, 4.11%; and shelf life, 15.24 days.This result may be due to the ability of the organic granules to supply plant nutrients and the required organic matter in a sustained manner.This organic matter influenced the vegetative growth, yield components, and quality of tomato fruits by releasing nutrients, enhancing soil physical and chemical properties, and promoting the root activity of tomatoes. 24Related studies have shown that organic manure increases the organic matter in soil, resulting in higher soil bacterial activity, which breaks down the organic matter and releases NPK and other nutrients that are positively influenced by soil enzymatic activity, ultimately improving the sugar/acid ratio.The slow release of nutrients from organic granules promotes the gradual development of tomatoes, leading to better quality fruits, as reflected by the improved taste, texture, and nutrient content.This finding agrees with that of Du et al. 25 The results of our study also aligned with that of Gao et al., 26 who found that TSS, vitamin C, and lycopene were significantly improved by organic fertilizers relative to inorganic fertilizers due to the release of nutrients, addition of organic matter, and creation of favorable physical conditions in the soil.

Nutrient (NPK) uptake
Organic granules and inorganic fertilizers significantly influenced nutrient uptake by tomato plants (Table 5).The application of 100% of the recommended NPK using synthetic NPK granules (Urea, DAP, and MOP) led to values that surpassed those obtained with the synthetic fertilizers and organic granules for nutrient uptake at the flowering (NPK -18.40,9.98,and 27.48 kg/ha),   that obtained with the application of 100% of the recommended NPK using organic NPK granules.Regarding fruit quality, soil fertility, and soil microbial population, the application of 100% of the recommended NPK using organic NPK granules was superior to the other treatments.Hence, the use of organic NPK granules to deliver 100% of the recommended NPK is a viable and environmentally safe nutrient management practice to obtain better tomato yield and quality.Further studies are required to assess the combined effects of graded levels of NPK through inorganic fertilizers and organic NPK granules on the productivity and quality of tomatoes.

Table 1 .
Effect of organic granules on growth and yield attributes of tomato Values not sharing a common superscript letters (a, b, c, d, e, f, g, h and i) differ significantly at p < 0.05 Duncan Multiple Range Test (DMRT)

Table 2 .
Effect of organic granules on fruit, stover yield and quality parameters of tomato

Table 4 .
Effect of organic granules on quality parameters of tomato Values not sharing a common superscript letters (a, b, c, d, e, f, g, h and i) differ significantly at p < 0.05 Duncan Multiple Range Test (DMRT).

Table 5 .
Effect of organic granules on nutrient uptake (kg/ha) recorded at different stages of tomato 30Similar results were

Table 7 .
Effect of organic granules on microbial population recorded at different stages of tomatoValues not sharing a common superscript letters (a, b, c, d, e, f, g, h and i) differ significantly at p < 0.05 Duncan Multiple Range Test (DMRT)