On the volatilisation note. It is better to be spreading at cooler temperatures because ammonia volatilises more the higher the temperature is so in that respect it would be better to spread during the winter as long as ground conditions are right and there’s no chance of runoff."The Farm Yard Manure becomes ready for use in 4 to 6 months and on an average it contains 0.5%N, 0.2% P2O5 and 0.5% K2O. Application of 10 tons FYM to the soil gives 50Kg N, 20Kg P2O5 and 50 Kg K2O. Out of this 30% of N, 60-70% of P2O5 and 75% of K2O is available to the crop in the first year of application and the rest of the nutrient is available in the subsequent years.Considerable amount of N in FYM is lost during preparation and storage mainly as NH3 volatilisation and or NO3 leaching. The values normally reported as dry equivalent values and there was only superficial moisture removed."
So for each 10 tons of FYM spread;
15kg of nitrogen,
13 kg of phosphate,
37.5kg of potash
is available to the crop in the first year.
I guess that means it would be the equivalent to spreading an artificial NPK of 0.15/0.13/0.375.
While a "Considerable amount of N in FYM is lost during preparation and storage mainly as NH3 volatilisation and or NO3 leaching".
I always thought autumn spreading was very effective here.