posted this on Crop Talk.
"1. Yield variation of less than 2t/ha to 4.5t/ha on the monitor. What really gives me some issue is that good yields are in poor CEC soils (5-7 cec) and the good CEC soils (10-15) (give good corn and wheat crops and good residues). "
Yes, we seem to get as good soybean yields in our poorer soils as we do our better soils. Some speak of ground better suited for soybeans and some suited for corn or wheat or other crops.
I do get as good a soybean yield in my low CEC soils as I do the higher ones. The higher ones seem to out yield the lower CEC soils in corn. CEC may not be the factor.
Remember soybeans originated from China and never got here until my childhood in the 1950's. I remember our first soybean yields in the 1970's and we thought they were big yields, 50-70 bushels per acre. Soybeans thrived here and some of my neighbors have made a living off soybeans their whole lives. We struggle to stay at or get above these yields.
2 ."Calcitic lime seems to have helped and may be has meant more freely available calcium in the low CEC land. How many recommend shooting for 65-70% Calcium saturation over and above getting acidity sorted out. "
I have correlated soybean yield to base saturation calcium and generally the higher the calcium level, the higher the yield.
3. "I apply 200kg/ha of granular 10:18:24:7s and then 100kg/ha AS. I also did some bands across the field with UREA at 100kg/ha and seem to be able to see that on the monitor. I consider my general fert programmes quite generous and would not say this is low testing ground. I put this urea on late because in our experience too much N early can cause too much vegetative growth-hence v.poor yield."
I can yield an economic return from fertilizer to soybean yield and profit on any soil. They need to be treated as a first crop, not a second crop. I am using 100 lbs AMS to melt down residue and feed microbes with a similar amount of phosphate and potassium fertilizer per crop with good results. Better than when I don't use any but I cannot show you exact figures. I add micronutrients from the last crop tissue result. Still, we seem to be stuck in a rut yield and profit wise.
If I add 100 lbs of calcium pellet lime to urea or AMS, I seem to stimulate the calcium nitrate sulfur complex with AMS and the soil looks and acts healthy and the crops are good.
4. "ABM innoculant does not appear to work (planter box graphex) even at double rate. Care has been taken to put no moly on seed-could be the syngenta Apron Star? I do put moly in foilar sprays. Leaf tests at flowering show no obvious deficency-although N is on the low side."
This is where we are really different as I've seen good results from every ABM product. What is the difference? I do not know.
What causes your 4.5 tonne yields compared to your 2 tonne yields? What causes my 70 bushel yields from my 50 bushel yields? Everything I wrote above seems to get me closer to that 70 bushel or his 4.5 tonne yield level.
What do you think?