EAST LANSING, Mich. — The soybean cyst nematode is the most significant robber of yield in North America. An article published in the “Journal of Nematology” in March 2013 detailed experiments conducted to determine the effects of liquid swine manure and chemical fertilizer phosphorus (P) and potassium (K) on soybean and corn yields, and soybean cyst nematode populations on two soils—one considered a soybean cyst nematode suppressive soil and one considered a soybean cyst nematode conducive soil.
For each site, the experiment was split-plot design with three crop sequences as main plots and three fertility treatments as subplots. The three crop sequences, over two years, were (1) a susceptible (non- soybean cyst nematode resistant) soybean variety followed by the same variety in year two; (2) a soybean cyst nematode-resistant soybean variety followed by a susceptible soybean variety in year two; and (3) corn followed by a susceptible soybean variety in year two. The fertility treatments were swine manure, chemical fertilizer P and K, and no fertilizer/manure as a control.
Swine manure did not reduce soybean cyst nematode egg populations, but did result in 31 percent lower soybean cyst nematode stage-two juvenile (J2) populations at the suppressive site 45 days after planting the soybeans.
The swine manure treatment also reduced another plant parasitic nematode—the spiral nematode by 52 percent compared with the chemical fertilizer and control 45 days after planting.
The crop sequences 1) corn followed by a susceptible soybean variety and 2) a soybean cyst nematode-resistant soybean variety followed by a susceptible soybean variety reduced the soybean cyst nematode egg and J2, but increased spiral nematodes at the suppressive and conducive sites.
An increase of 22.3 bushels per acre and 8.0 bushels per acre in yield of susceptible soybean was observed in manure and P and K treatments, respectively at the conducive site.
The researchers concluded that their study showed soybean yield responded positively to applying liquid swine manure and chemical P and K fertilizer, and the manure was more effective than the fertilizer. Fertility also plays a role in developing sustainable strategies to manage soybean cyst nematode. The researchers also concluded that the soybean yield advantage of using soybean cyst nematode-resistant varieties in a nematode-conducive soil may at least be partially replaced by fertilizer input, especially liquid swine manure.
— Robert Battel, Michigan State University Extension
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