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Colby, Kansas | Steven:
I think the reason folks in your area are seeing a response to rotation is tied to the fact that it results in actually having some residue on the ground, and wheat stubble is one of the best to have. I would argue that the yield improvement has nothing to do with fertility and everything to do with reducing evaporative losses. Having that stubble in place would make a huge difference on fallow efficiency (and preseason irrigation efficiency) in between the time the wheat is harvested/terminated and the cotton is planted. Having the cotton planted into the stubble would make a huge impact on in-season irrigation efficiency in the cotton crop also. KSU research at Garden City has shown that going from a conventional till irrigated scenario to having some residue on the surface can cut evaporative losses by as much as 50%, reducing the E in ET from 30% to around 15% of the total. On fully irrigated corn this can save us as much as 4" of water and result in the same yields, or could potentially result in higher yields with the same amount of water. Beings your even in a slightly higher evaporative environment I would expect the impact to be as big if not bigger.
Sudan might very well be a good fit, as long as if you cut it for feed you leave some to serve as residue. I'm afraid sesame will result in loosing the evaporation prevention benefits, as from my experience the residue won't last long. Wheat residue is just hard to beat,, thats the only way we are able to raise good dryland corn/sorghum up here, and typically it shows, a poor wheat crop with poor residue typically results in a poor subsequent row crop. I think using beef manure is an excellent route and could do a lot of good for the typical soils in West Texas (at least those I have some minor familiarity with). On those very low P testing fields, I think band application of P-starter at planting would be beneficial.
I probably just stated some stuff you already knew, not trying to be preachy, just sharing some thoughts.
Regards,
Lucas
Edited by LHaag 12/6/2011 22:33
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Fertility
