Alternate Grain/Bean Rotations for Optimized Economic Yield in Northeast Organic Farming
Rapidly burgeoning organic markets for milk and wheat present both opportunities and challenges to growers. Optimizing growing grains and beans to serve either animal ration formulation or human consumption is a basis for this study. Vicia faba beans are explored for alternative animal ration protein and spring and winter wheats for dual-purpose, animal and human consumption. Economic pressure means that, unless wheat grading moves grain to animal categories, all wheat most likely goes into human food chain markets. Quality limitations of grain that act to shift markets are evaluated and consist of protein content (bake quality) and partial mold spoilage. In comparing spring with winter wheats, we find less planting and weed pressure for winter varieties, but protein is lower. Fungal spoilage potential is high for wheats harvested or stored in the Northeast under conditions exceeding 65 percent relative humidity; and this may be the single greatest determinant of markets for wheat.
There is a rapidly growing market in the Northeast for organic milk and wheat products. Organic milk growth is limited on the one hand by consumer demand but more importantly on the supply side by availability of affordable organic grain rations. Therefore, it is important to optimize the growing of grains and beans. However, an overriding concern is that, given the dynamics of the organic marketplace, other factors play an important role in determining which organic products may be economically delivered to farms versus used for human consumption. One example is that organic soybeans will always be sold into human food chains. Therefore, protein rations must include lower value but suitable crops such as Vicia faba, previously used elsewhere by organic growers, for mixed rations. Furthermore, some mechanism for screening for quality must exist for wheat and other grain products; otherwise it is very likely that human consumption demand will mean that local grown wheats will not enter animal markets at all, putting dairy growers back into the situation.
During the 1999 and 2000 growing season, we evaluated yield, moisture, protein, quality, and mold condition of selected grains and faba beans. Spring wheat is generally higher in protein, yet exposes organic growers to vagaries of early planting conditions and significant weed pressure. Winter wheats performed well in our trials and had fewer constraints in terms of annual weeds, while providing more leeway for late summer planting when conditions in Maine are nearly ideal for soil work. Fall plant dates for winter wheat from late August to the end of September have worked well.
A significant constraint exists in moisture conditions of wheat harvests. This factor alone may emerge as the principal determinant of quality. Field moisture content of wheat after harvest for 12 cultivars ranged from 7.1 to 17.9 percent, indicating some grains may need significant additional drying to prevent mold spoilage. A new technique to measure grain moisture using hand-held meters was used. We also applied a spoilage detection approach by a quick measure of CO2 respiration in grains; this has been shown previously by Purdue University and Iowa State research to be a significant indicator of remaining storage life.
The remaining storage life determined for wheats harvested in Maine under typical conditions gave values of 150 down to 30 days. While most wheats were sold, our tracking indicated that certain ones that scored low in tests for remaining storage apparently continued to spoil and were discarded before final sales into human markets. Economic losses from poor storage need to be better understood. A grading system based on harvest and storage moisture and respiration traits would help select wheats for animal ration markets. Vomitoxin concentration (a mycotoxin from Fusarium) is frequently used in the trade, yet alone it is not enough to safeguard wheat storability. However, alternative marketing of vomitoxin-contaminated wheat is already recognized—even though flour mills and other processors are not likely to purchase grain with vomitoxin contamination in excess of 2 ppm, dairy cattle are relatively unaffected by moderate levels of vomitoxin, and individual dairy farmers and local dairy feed mills may be interested in buying moderately contaminated wheat, albeit at lower price than normal flour mill prices. Wheat producers should contact potential buyers about standards. In Woods End’s trials, moisture equilibration constants show that, at atmospheric RH above 65 percent, significant moisture-related problems may ensue in at harvest and during storage. The window of opportunity can be as low as 30 days if moisture is too high.
The protein content of 17 varieties of wheat examined from three farms ranged from 10.7 to 16.4 percent. The highest protein was for spring wheat on Woods End Farm with prior use of manure compost and a grass/legume proceeding in the rotation. Of all wheats on the three farms, four out of 17 fell below the 12 percent protein level arbitrarily set by some bakeries as the cutoff for baking quality, while six varieties but only one winter wheat were at or above 14 percent protein, which is considered excellent. Winter wheats selected from organic varieties developed in Switzerland based on tall stems and bake tests gave reliable performance and quality in Maine trials.
The impact from these studies is likely to be twofold. First, the results of these trials may act to bolster confidence in winter wheats. Winter varieties of wheat, though lower in protein, may help organic growers significantly with regard to annual weed control and wet-soil planting conditions encountered with spring wheats. Secondly, a grading system for wheat may be devised based on test traits and level of partial spoilage or storage history.
Reported November 2000
Purdue Univ – Dept of Agric and Biol Eng
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