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Martinsville, Ohio | Good article Jon. I have used that idea for years but order what is available. My soil can break it down. Now we have little choice, little DAP to be bought here unless you get your own from the river terminal and most farmers don't do that.
This stands out and makes you think of the glyphosate issue on Mn:
MICRONUTRIENT EFFECTS
Hossner and Richards (1968), working with a soil at pH 7.0 observed no difference in Mn uptake between DAP and MAP when no Mn was added to the P band, however, when 25 ppm Mn was added, both MAP and DAP increased Mn uptake but MAP had a greater effect than DAP.
Randall et al. (1975) compared the effects of MAP and DAP on soil Mn availability to soybeans on a Sebewa loam at pH 6.1 and, unlike Hossner and Richards, noted that DAP was more effective than MAP in correcting Mn deficiency. The higher pH, higher P rate (50 ppm P) and shorter growth period of the Hossner and Richards study might explain the difference in outcome.
Voth and Christenson (1980) conducted several experiments evaluating the effects of fertilizer sources on Mn availability. They conducted an incubation study using a Tappan loam soil and measured pH and DTPA extractable Mn in bands where MAP or DAP, KCl and Urea had been applied. After three weeks, sufficient nitrification had taken place to significantly depress pH in the band for both treatments below that of the check. In this study, MAP and DAP did not differ in reaction zone pH at three, five or seven weeks of incubation. Mn was elevated for both sources throughout the incubation including DAP at the three-week sampling. In other work by the researchers, sugar beet and soybean field studies at sites testing near a pH of 8.0 showed that tissue Mn concentrations were higher five to six weeks after planting when MnSO4 was band applied with MAP than when applied with DAP at a rate of 50 lbs P2O5/a (Christenson, 1981).
Good article, Jon. I have never seen the discussion on fertility programs like I have this year. I think most of us just stuck to the same program.
Again, you know me, it HAS to fit in my budget. We can only spend so much on the 17 nutrients but we all know we need them in some kind of balance, thus back to the soil test and tissue test.
Ed | |
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Is there a preference for MAP or DAP?
