Effects of Long Term Fertilization in soil science
- 1. Effects of long-term application of chemical fertilizer
- 2. • Indian fertilizer industry started in 1906 with SSP production at Ranipet near Chennai • But production received a boost from 1940s onwards with establishment of FACT and FCI in Kerala and Bihar, respectively • Now, India is second largest producer of fertilizers • Fertilizer production in India is 46 million metric tonnes while consumption is 63.92 million MT during 2022-23 • Fertilizers made us increase the agricultural production which was otherwise dependent on imports
- 5. • India is almost self sufficient in N production ( 57 companies produces nitrogenous fertilizers, out of theses 27 are Urea producing) • In case of Phosphorus, raw materials are mostly imported • Potassic fertilizers are mostly imported Status of India in Fertilizer sufficiency
- 6. • Since last half a century the with advent of fertilizer use in agriculture there was enormous research on the effect of fertilizers on crop productivity, nutrient content and quality. • Research grew in multi dimensions viz., fertilizer application, mode, doses, methods, interactions, effect on soil physical chemical, microbial properties besides, imbalances viz., antagonism, interferences, toxicity , deficiencies etc.
- 7. All-India NPK use ratio widened from 7.7:3.1:1 during 2021-22 to 11.8:4.6:1 during 2022-23. N:P:K 4:2:1 N:P:K 7.7: 3.1: 1 N:P:K 11.8:4.6:1
- 8. • The assessment of soil quality requires a systematic method for measuring and interpreting soil properties (Granatstein & Bezdicek, 1992). • Individual soil properties may not provide an adequate measure of soil quality and integrated soil. • The measurements of biological along with chemical and physical properties of soil are essential for evaluating the impact of organic amendments on soil quality (Min et al., 2003). • A soil quality index (SQI) would help with the interpretation of data from different soil measurements and show whether management and land use are having the desired effects on productivity, environmental protection and health (Granatstein & Bezdicek, 1992). How to asses the Effect of Long term Fertilization on Soil Properties
- 9. Continuous application of N fertilizers alone adversely affected the soil productivity leading to drastic reduction in yield to an extent of 75-80% in finger millet, maize and cowpea as P became limiting nutrient. There was a spectacular yield increase when N and P were applied together (40 to 80 %)
- 11. • The soil N reserve as reflected by total N was found to build up over years with all nutrient input systems except no manuring and sub-optimal fertilization • The soil K reserve in form of total K was found to decline slowly with intensive cropping irrespective of nutrient input • Continuous exclusion of S from fertilizer schedule did not show adverse effect on yields of finger millet, maize and cowpea; however, there was a yield reduction in recent years
- 12. • Application of NPK+FYM resulted in marginal to moderate improvement in DTPA extractable Zn over NPK treatment, indicating efficacy of organic manures in meeting micro nutrient requirements of crop. • Addition of Zn to maize crop in sequence did not bring any significant yield improvement Micronutrients
- 13. Soil Organic Carbon and its maintenance
- 16. Effect of Fertilizers on Soil pH • The form in which the nutrients are applied and their fate in the soil-plant system determine the over all effects on soil pH • Macronutrients (NPK) have the major effects on soil pH as they are added in much larger quantities to soil than micronutrients • Of all the major nutrients the Nitrogen is the main nutrient affecting soil pH; soils can become acidic or alkaline based on the type of N fertilizer • Nitrate based fertilizers are least acidifying, while ammonium based showed highest potential to acidify soil
- 17. • Ammonium based fertilizers will acidify soil as they generate two H+ ions for each ammonium molecule nitrified to nitrate • Nitrate based fertilizers have no acidification potential and actually can increase soil pH as one H+ ion is absorbed by the plant (or OH-) in the uptake of nitrate. • Soil acidification due to use of phosphorus fertilizers is small compared to that of Nitrogen (due to low amount of fertilizers used and lower acidification per kg of phosphorus)
- 18. • MAP, SSP, TSP all add P to soil in form of H2PO4 - ion, which can acidify soil with a pH greater than 7.2 but has no effect on soil pH in acidic soils. • The form of P in DAP is HPO4 2-, which can make acidic soils (pH < 7.2) more alkaline but does not have effect if pH >7.2. • Potassic fertilizers have little or no effect on soil pH.
- 19. • Soil BD decreased in M and CFM • Soil OM content increased significantly in M and CFM Soil
- 20. • The improvement in soil physical parameters in the plots with continuous application of NPK along with FYM may be due to the increase in SOC and that might have decreased BD and CDI (Reeves, 1997). • The Cmic content varied from 180 to 361 mg/kg, and the greatest was reported for the NPK+FYM treatment. • Application of FYM and P through chemical fertilizers enhanced Bray’s P. • Application of NPK along with FYM led to a significant increase in DHA, urease, acid- and alkaline-phosphatase activities in the rice soil Long term Fertilization Effect on Soil Physical properties
- 21. Effect of Long term Fertilization on Soil Microbes • Brings about change in composition of soil microbial community • Long term nitrogen fertilization decreases bacterial diversity and favors the growth of Actinobacteria and Proteobacteria in agro-ecosystems across the globe • In fungal communities, Ascomycota was the dominant phylum (69.1– 72.6%), followed by Mortierellomycota (3.7–14.4%), Basidiomycota (2.3–7.5%), and Mucoromycota (0.5–3.4%).
- 22. Relation between Composition of Soil Microbial Community and Soil Physicochemical Properties • Proteobacteria was significantly positively correlated with soil OM and TN, whereas • Actinobacteria was significantly negatively correlated with soil TN, AN, and pH
- 24. 1) Non-fertilization control (CK), 2) chemical fertilization only (CF), 3) organic manure fertilization only (M), and 4) chemical fertilization plus organic manure (CFM). • Compared with CK, soil organic matter, total nitrogen, available nitrogen, available phosphorus, and available potassium contents were higher in M and CFM, whereas soil pH was significantly lower in CF. • Abundances of dominant soil bacterial phyla Proteobacteria, Bacteroidetes, and Gemmatimonadetes were higher in M and CFM than CK. • Abundances of dominant soil fungal phyla Ascomycota was lower in CFM than in other treatments. • The pathogenic fungi Fusarium, Paramyrothecium, Cladosporium, and Alternaria had the highest abundances in CK and CF, whereas abundances of the beneficial fungi Mortierella were significantly higher in M and CFM than in CF and CK. • Overall, CFM maintained higher soil fertility and a healthy ecosystem because it increased beneficial microorganisms and inhibited pathogenic microorganisms, whereas CF increased the risk of crop infection with soil-borne diseases. Case Study
- 25. CONCLUSION • The CFM maintained high soil fertility, suitable pH, and stable microbial community composition, suggesting it was the best measure among the three amendment types • In contrast, CF decreases soil OM contents and increased the risk of soil acidification, while pathogenic microbial taxa abundances significantly increased • Indiscriminate use of chemical fertilizers, and decreased organic fertilizer use, can lead to ecological problems, including reductions in soil organic matter, soil slumping, groundwater contamination, and reduction of soil productivity
- 26. • Fertilization alters soil fertility by affecting nutrient levels, such as those of soil organic carbon (C) and total nitrogen (N), which directly composition of soil microbial communities. Fertilization can also indirectly affect soil microorganisms by altering soil properties . • For example, a decrease in soil pH following N application was the primary cause of changes of bacterial communities observed that changes in C/N ratios caused by fertilization significantly affected the distribution of soil microbial communities. • It was concluded that Proteobacteria and Gemmatimonadetes were not affected by fertilization and soil environments, whereas abundances of Acidobacterial and Actinobacterial were negatively correlated with fertilization treatments. Fertilization may also influence below-ground microorganisms by affecting above-ground plant processes.