The P application rates equivalent to removal of P crops are recommended to soils sufficient or adequate in soil test P. In India the Fertilizer rates recommended range from 40 to 80 kg/ha P2O5. This is equivalent to 17.5 to 35 kg P/ ha.The P removals in many crops range from 8 to15 kg P/ha.If P is applied asper replacement of crop removal approach, nearly 50 per cent P can be saved by farmers.If lower rates of P is applied.There will be better utilizaion of applied P.

P fertilizer is not depleted from soil, but it is usually fixed on clay particles. Plowing and disking help to release a good quantity every time. Side dressing of P is very helpful to reduce the cost of this fertilizer. Regards.

Dear Dr Annangi Subba Rao . You can use alternative for phosphate fertilizer by :

• Manures. Animal manures like rabbit, duck and chicken hold nearly as much phosphorous as inorganic fertilizers.
• Bone Meal.
• Composts.
• See the following link: https://homeguides.sfgate.com/phosphate-fertilizer-alternatives-20465.html

Kindly see also the following useful RG link: Article An alternative to mineral phosphorus fertilizers: The combin...

Also check please the following very good RG link: Article Possible use of struvite as an alternative phosphate fertilizer

Yes, we can. Crop-absorped P could be transformed into organic P thereby given crop is fermented. Thus, we could use fermented crop to fertilizer other crop.

Possible use of struvite as an alternative phosphate fertilizer

Application of P fertilizer equivalent to maximum P use efficiency i.e., 20-40% PUE for any crop, and also soil test based P fertilizer application example if initial available P in soil is high, apply 75% of recommended dose and if initial available P is low apply 125% of recommended dose and if initial available P is medium then apply recommended dose will be efficient in reducing P fertilizer usage, application of organic manures and P solubalizing bacteria like PSB will also helpful in improving PUE and reducing P fertilizer consumption. If application of P fertilizer exceeds the crop requirement, it will result in P biuld-up in soil irrespective of the soil type which results in more P fertilizer wastage.

Check https://link.springer.com/article/10.1007/s00374-019-01430-2

https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/phosphorus-fertilizers

Also check https://www.fao.org/3/a1595e/a1595e.pdf

https://www.tandfonline.com/doi/full/10.1080/00128325.2015.1040640

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-95162012000300015

That is a good strategy, but I don't how the farmers particularly small scale farmers can measure this and apply.

The use of organic manure like rabbit and chicken can be alternative sources

Kiprotich Kiptum P removal data of a crop can either be generated from field experiments or obtained from literature from comparable ( to a farmers's field yield) level of a particular crop.The following paper published by our team gives good idea of the approach put up by me for discussion.

Organic manure based phosphorus supply strategies: Effects on crop yield and soil test maintenance P requirement under soybean-wheat system. Biological Agriculture and Horticulture 24(1)21-34 DOI:10.1080/01448765.2006.9755006

I believe this approach will hold good in soils in which due to continued application of P fertilizers there is enough buildup of P.

Bijay Singh I agree with you.The idea is proposed by scientists from Europe.We also did some studies at IISS, Bhopal.This is ideally suited for soils adequate in available P. In our studies for soybean-wheat system where we applied only fertilizer P, we had to apply 25 to 50 per cent extra P to take care of fixation losses and get similar yield level of crops which received full dose of P. When we applied all the recommended P through farmyard manure, the amount of manure P equivalent to crop removal of P was adequate.As we understand, the manure supplied P through mineralization of P present in manure and also mobilized some soil P through production of organic acids /protons during decomposition.integrated use of manure and fertilizers may also help to reduce the recommended fertilizer dose t to nearly half.We need demostration trials in this direction on farmers' fields.

Hence to follow this idea we need to adopt the Soil test crop response (STCR) approach for balanced application of P as well as other fertilizers.

Ayesha Fatima Yes, we are aware soil test based application of fertilizers is the best way for efficient use of all fertilizers including P fertilizers. In STCR approach for each soil test value of P, we can get P recommendation from calibration table or fertilizer adjustment equation. Even if farmers apply around 80% of the recommended fertilizer P, they get reasonably high yields(nearer to target) in favourable years.If we follow integrated nutrient management approach, we can save on the cost of fertilizer P and can get some benefit of legacy or residual P by mobilizing it through organic manures or through biofertilizers application.In the absence of soil test based recommendations in the soils with near adequate P, one can apply P fertilizers equivalent to P removal by crop.If fertilizer P is alone applied one can apply at least 25% more P.If manures are applied alone or with fertilizer P, the fertilizer P equivalent to crop removal of P can be applied without much yield loss and saving on fertilizer P. More of such demonstration studies are required on farmers" fields.

Yes, to the great extent it will work. Remember, soil pH play greater role in availability of the P. If the amount of phosphorous will fix and convert into unavailable form, it may not be fully available to the next crop and cause deficiency. Therefore, it will not be wrong if either we use little extra of use some Biofertilizers to enhance its use efficiency.

Yes, but it is not sure all the applied P will be available to crop. Because P is a complicated eliment. Integrated approach would be more sound technique for managing P shortage; use of P solublizing microbes, crop rotation, nutrient budget based P management.