We all know that fertility levels are inverse to the fertiliser doses. Sometimes higher doses than recommended are used for specific benefits in soil as well as in crops. But unnaturally in soil highly fertiliser soils greater than recommended doses become responsive. What might be the probable reasons for this situation.
The recommended dose of a specific crop is broad-based sometimes, which is also decided based on the soil status of a large area, economic profitability without considering site-specific requirements or varietal potencial.
For example, for Rice state recommended dose is 80-40-40, which is broad-based, so there is the possibility of a positive response to added extra nutrient specially nitrogen, even if high fertility status. But at some time, chances of antagonistic effect on another nutrient.
I also can assume that a higher dose than the recommended dose will not be responsive greatly in high fertility soil when the recommendation is site-specific.
Both soil fertility and soil productivity are different aspects. The higher soil fertility not directly responsible to crop yield but soil productivity directly proportional to crop yield. if we added more fertilizers means we increasing soil productivity. Hence, crop yield increases.
Indranil Das your query has 2 erroneous words- unnatural can be deleted & "fertiliser" should read "fertile" after "highly" I guess. Your observation is due to (1) "greater availability" of added fertilizers. Soil may be fertile in health tests but minerals may not be bio-available for crop growth, being locked. Added fertilizers especially Nitrogen can quickly boost biomass growth. (2) But in the long run such growth benefit of excess fertilizer addition may not last & soil may be "usar" (salty) like in Punjab & Haryana with productivity decline. (3) if carbon is deficit, high nitrogen can be toxic & reduce yield in future, as C:N ratio recommended is 25-30, failing in "usar" lands. (4) Crop quality may be suffer by excess fertilizers.
I agree with you Dr. Ghate that those words are erroneous. Unfortunately, I didn't get my answer. Yes there may be fixation but that to limited for certain nutrients (like P, K etc) not all. My question was very specific. We all have crop specific fertiliser (N-P-K) recommendations for different fertility levels (H M L). These recommendations are based on location specific trials upon specific crops (varieties) considering their uptake etc etc. Generally for high fertility soils (for any nutrients) lesser doses of fertilisers are recommended. But in some of my experiment I observed better response of crop with higher than recommended doses of fertiliser in higher nutritional status of soil or highly fertile soil with particular nutrients. What might be the reason for this.
Dr. Mohanta and Dr. Ghate raised some important and I agree with them also. But I need some more points to justify this situation.
- Badges
- Science topic
- Similar topics
- Clinical Pharmacology
- Dosing