With Soybean target yield of 18 quintal per acre, I am applying (all dose per acre)
40 kg P2O5 (soil Olsen P is 20 ppm),
45 kg murate of potash (soil K 180 ppm),
10 kg sulphur (gandhak)
Micronutrients mix, sulphate salts of
10 kg Zn and Fe each; 2 kg Cu and Mn
And 1kg Mo and B.
In addition 2 T Vermicompost
(Along with Rizobium and PSB seed treatment)
In highly cited review paper on Soybean N uptake, there is reference of 200 Kg N uptake (above ground biomass) by 20 qtl / acre Soybean. With 20% in below ground. This is 240 kg/acre. Assuming 40 % uptake from BNF, this works out to be ~ 140 kg. However excess basal dose negativity affects nodule establishment. So I propose to experiment a split application: Basal 40 kg (Ammonium in DAP + Urea). Which should be the next points of applications?? And in what form?
donot go for basal dose of urea when you are already adding DAP.
SIMILARLY INTERACTION OF ZINC WITH P IS WELL KNOWN FOR BLOCKING OF NUTRIENTS.
SOYBEAN IS BASICALLY A LEGUME AND CAN FIX ATM, NITROGEN VERY WELL.
SPLIT APPLICATIONS OF N SOURCE SHALL BE BETTER OVER TIME FRAMED MANNER.
I agree with Kulvir Singh in the inadvisability of applying nitrogen on soybean. Soybean is sensitive to low soil acidity if you can get a soil pH reading liming maybe one of your best options for optimizing soybean production. In relation to nutrient application the phosphorus is best applied close to the seeding area to stimulate early growth and rooting. The potassium is best applied at flowering to stimulate the translocation of photosynthetate into developing pods. In terms of micronutrients if the pH is right you might not have any issue at all. If in the vegetative stage you get chlorosis the type of micronutrient deficiency can be found by leaf tissue analysis. In alkaline soils iron and manganese deficiencies as well as zinc are possible. If you have accessibility of rock phosphate and you have an acid tendency soil I would suggest mixing vermicompost with phosphate as your starter fertilizer then use potassium at mid flowering. If you have any soil or leaf analysis I would be glad to give an assessment based on my experience.
The pH is near neutral (~ 7.5 to 7.8)
With only NPK basal (25:50:20) and some organic matter. Farmers have observed yield upto 10 - 12 quantal per acre.
Whereas in some other soils, similar pH and EC.. yield could b up to 22-24 quintal per acre.
While I am also Experimenting with use of dose similar to observed high yield, I propose to experiment with the N based on some literature evidence and observation as stated in the question.
Would b grateful to receive advice on, which would be the two ways (points DAS) to test split N application and what form of N fertilizer.
on the basis ofexperimental results it can beapplied 60kg N+80kg P with split application of Nitrogen of 50 % N at the time of flowering stage during kharif season gave higher yields
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