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A study on “Matrix based slow release fertilizer for increasing the nutrient use efficiency in the Onattukara sandy plain” was carried out during 2017-2019 in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani. The objective of the study was to develop low-cost matrix based slow release fertilizer using local biodegradable agro waste and to evaluate the effect of this slow release fertilizer in increasing nutrient use efficiency in the sandy loam soils of Onattukara. The study comprised three parts viz., development of matrix based slow release fertilizer, incubation study and evaluation of the effect of matrix based slow release fertilizer in increasing nutrient use efficiency. Different combinations of biodegradable locally available materials like rice husk ash, clay, cow dung, rice husk, coirpith compost, vermicompost and neem cake were used to develop a suitable matrix. The matrix with 1: 1: 0.5: 0.5: 0.5: 0.5: 0.5 composition was selected based on its high pH, low electrical conductivity and low cost of production. The stability and dissolution was also studied under controlled condition.
The best combination of matrix (1: 1: 0.5: 0.5: 0.5: 0.5: 0.5) was selected to entrap fertilizers at various proportions of matrix: fertilizer viz., 1:1, 2:1, 0.5:1 and matrix alone. Granular and disc forms of these combinations were developed and used for incubation for a period of two months to study the nutrient release pattern of N, P and K. Soil samples were collected at 15 days interval for nutrient analysis. The nutrient release pattern was different for N, P and K. The 2: 1(matrix: fertilizer) granular formulation was selected based on the gradual release pattern and the highest peak of nutrient availability of N, P and K even after 2 months.
Effect of matrix based slow release fertilizer in increasing nutrient use efficiency was evaluated by using tomato variety Vellayani Vijay as test crop and the pot culture experiment was conducted at Onattukara Regional Agricultural Research Station, Kayamkulam during November,2018 - January,2019. The 2:1 granular formulation was selected for entrapping NPK fertilizers for the pot culture experiment.The experiment consisted of ten treatments and they were T1 (Recommended dose of fertilizers and organic manure as per POP), T2 (Recommended dose of fertilizers as basal application),T3 (Recommended dose of fertilizers in two splits),T4 (Matrix entrapped recommended dose of fertilizers as basal application), T5 (Matrix entrapped recommended dose of fertilizers in two splits),T6 ( Matrix entrapped 75 % of recommended dose of fertilizers as basal application),T7 ( Matrix entrapped 75% of recommended dose of fertilizers in two splits),T8 ( Matrix entrapped half dose of recommended dose of fertilizers as basal),T9 (Matrix entrapped half of recommended dose of fertilizers in two splits) and T10 (Matrix alone).
Growth, yield and quality of tomato increased significantly due to the application of organic matrix based fertilizers. The highest plant height (35.6 cm) was recorded in the treatment T9 and was on par with T1, T3, T5 and T7.The treatments did not show a significant influence on number of branches per plant, days to first flowering and days to fruit set. Treatment T9 recorded the highest fruit set percentage (80.3%) which was on par with treatments T1, T5, and T7.The treatment T9 recorded the highest value for all the yield attributes and yield. The highest number of fruits per plant (32.3) and yield per plant (0.79kg) was recorded by treatment T9 and was on par with T1, T5 and T7. For fruit weight, treatment T9 was found to be on par with all other treatments except treatment T10.The treatment T9 recorded the highest value for the quality parameters such as TSS (5.33 %) and ascorbic acid (22.3 mg 100g-1). The treatments did not show any significant influence on Lycopene content of fruit. Soil analysis after the experiment showed that the pH increased from the initial value of 5.28 to the highest value of 5.98 which was recorded for the treatment T10 and was on par with all treatments except T1, T2 and T3. The treatments with matrix entrapped fertilizers recorded a higher pH as compared to the treatments without matrices. The highest value of EC (0.68 dS m-1) was recorded by T5. The treatment did not show a significant influence on organic carbon content. In the case of primary nutrients, for both available N and K, treatment T5 recorded the highest status (250.9 kg ha-1 and 215.8 kg ha-1) and was on par with T4, T6, T7 and T9. Available P status was the highest in T5 (53.37 kg ha-1) and was on par with treatment T4, T6, T7, T8 and T9. The highest value for exchangeable Ca (248.89 mg kg-1) and Mg (60 mg kg-1) was recorded for treatment T5 which was significantly superior to all other treatments. Treatment T5 recorded the highest value for available B (0.281 mg kg-1) and Zn (0.519 mg kg-1) also and was on par with T4, T6, T7, T8, T9 and T10. The results of the plant and fruit analysis revealed that the treatment T9 recorded the highest value for N, P and K content in index leaf (2.78% , 0.195% and 1.77%), plant (2.14%, 0.538% and 2.62%) and fruit (3.69 %, 0.555% and 2.20 %), respectively, which was on par with T1, T5 and T7. In the case of Ca, Mg, Zn and B content, the treatment T9 recorded the highest value for index leaf (0.186 %,0.168% , 16.15 mg kg-1 and 4.9 mg kg-1), plant (0.149%, 0.165% ,15.81 mg kg-1 and 4.4 mg kg-1) and fruit (0.157%, 0.149%, 16.89 mg kg-1 and 1.35 mg kg-1), respectively and was on par with all other treatments except T1, T2 and T3. Treatments did not show any influence on S, Fe, Mn and Cu content in index leaf, plant and fruit. There was no incidence of major pest and disease in the crop. Treatment T9 recorded the highest net income (Rs.230097/-), B: C ratio (2.1) and nutrient use efficiency.
From the investigation it can be concluded that, treatment T9 (Matrix entrapped half of recommended dose of fertilizers in two splits) was the best treatment in which the yield increased by 13% compared to POP recommendation and B: C ratio increased from 1.69 to 2.1. Organic matrix based slow release fertilizer was found to be effective under Onattukara condition for increasing the nutrient use efficiency from 18% to 44%. Fifty per cent reduction in the recommended dose of fertilizer was achieved by this matrix based slow release fertilizer formulation. This slow release fertilizer technology reduced the cost of cultivation and leaching loss of nutrients and increased the nutrient use efficiency and yield in the Onattukara sandy plain.