Changes in cropping systems or management practices often lead to unfamiliar and unforeseen problems. However, if the problems are fertility-related, then agronomic tests can make them relatively easy to solve. Plant tissue analysis, in particular, offers quick, precise and inexpensive diagnosis as well as recommendations for management and yield optimization.
The N.C. Department of Agriculture and Consumer Services urges farmers to watch their crops closely for growth problems. The best way to prevent yield loss is to detect problems early. This spring, the department?s Sandhills Research Station in Jackson Springs used tissue testing to diagnose a wheat nutrition problem, address it in a timely manner and reap an acceptable harvest.
Sandhills faced an unusual set of circumstances last fall. Because of favorable prices, station manager Jeff Chandler planted 33 acres of wheat instead of the traditional cover crop of rye. On the station, where small grains are grown in rotation with research plots of soybeans and cotton, six years of liming to accommodate cotton production had led to a gradual rise in soil pH.Â
?We saw the first signs of trouble early, when the wheat was 4 to 6 inches tall,? Chandler said. ?Growth was weak, yellowish and spotty. We speculated whether it could be a herbicide problem or whether the previous cotton crop had used more nutrients than we expected. We lime and fertilize according to soil test recommendations, so we weren?t convinced there was a nutrient problem.?
Extra nitrogen and sulfur were applied to help the crop green up. When that didn?t work, Chandler asked NCDA&CS regional agronomist David Dycus for his assessment. The two men frequently brainstorm to solve problems, and last year Dycus had helped Chandler confirm an infestation of stubby root nematodes in field corn.
Tissue analysis diagnoses problem
?My first thought was manganese deficiency, Dycus said, but I took diagnostic tissue samples to make sure because I know the station does a good job of soil sampling, and the soil reports didn't seem to indicate anything out of line. Sure enough, tissue test results showed clear manganese deficiency in the stunted, yellow areas.?
Chandler was surprised by the results. In the 50 years that rye has been grown on this station, we've never had an issue with manganese deficiency, he said. With wheat, the problem showed up right away.?
Manganese deficiency is more apt to show up on sandy soils when pH is high, Dycus said. Workers had applied additional lime to the station?s fields in recent years in an attempt to reach the higher target pH of 6.2 for cotton.
If rye had been grown as in previous years, the problem may not have shown up so dramatically, Dycus said. In wheat, however, manganese problems are readily apparent.?
With the problem pinpointed, applications of foliar manganese were prescribed and the crop began to improve. Response is usually seen within a week. In May, yields ranged from 50 to 60 bushels per acre, a respectable harvest for the Sandhills area.
Now that the manganese issue is known, Chandler can be proactive in addressing it. The station will be paying particular attention to this summer's soybean crop. Manganese deficiency tends to be even more obvious in soybeans than in wheat. Since soybean plants are bigger, it is easier to see yellow patches across the top of the field.
If the economic forecast for wheat continues to remain profitable, anyone considering growing it, especially in the Sandhills, should remember that all North Carolina growers have access to the same affordable agronomic testing services used by the research station. Analysis of a wheat tissue sample costs only $5. Regional agronomists are available statewide to make on-site visits and help solve nutrient- and nematode-related problems. Contact information for these advisers is available online at www.ncagr.gov/agronomi/rahome.htm.