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Fluid Journal : Fluid Journal 1993-1995
1 Fluid Journal Winter 1995 Summary: Reduced-till systems require special evaluation of all inputs if the crop is to perform to maximum capability and produce high yields. Among the essentials to consider are: hybrid selection, plant population, pest management, adequate drainage, and proper nutrient management. Through research, strategies have been developed to overcome the problems of stratification, volatilization, and accumulated organic matter that impede yields. In addition, strategies have been developed to promote plant root growth--- another key in producing higher yields. rop production is the optimization of the use of sunlight, nutrients, and water by plants to make carbohydrates, oil, and protein. For reduced tillage systems, a producer should evaluate how each input can be managed to enable the crop to perform to its maximum capability and produce high yields. Achieving optimum yields in such a system involves a number of considerations. Hybrid. In the early spring, reduced-till soils are often cooler than conventional-till soils by 2 to 4 degrees F. The cooler temperatures usually will delay planting 7 to 10 days. Under cooler conditions the seedling may be slower in emerging. Hybrid or variety selected, therefore, is critical for good emergence. Seeds with good vigor should be selected to ensure good emergence. Delay may also require selection of shorter-season varieties to ensure maturity. If residue levels are unusually high, the use of row cleaners may be warranted to increase soil temperature in the row. This should decrease the time it takes for seedling emergence. Other criteria for uniform emergence are good seed/soil contact, proper planter setting, and, of course, waiting until soil conditions are suitable. Plant population. Growers must not only select proper hybrids to achieve optimum yields in reduced-till systems, but also account for plant population. Work by Olsen at Rocky Ford, Colorado, has demonstrated that high plant population---along with top varieties, high levels of soil fertility, and good water management--- was among the key ingredients that produced corn yields more than twice the Colorado average (Figure I). Note that as plant populations of two hybrids increased from 25,000 to 37,000 plants/A, yield responses to nitrogen actually increased. In all cases of Olsen's work, high rates of nutrients were the rule. Pest management. Pest management is altered when there are high residues. Residues may harbor disease and insects a producer normally does not encounter with conventional-till. Lower soil temperatures by Dr. Jay W. Johnson R RRRRu le N umberOneforHighY ule NumberOne for HighY ule Number One forHigh Y ule Number One forHigh Y ule Number One for High Yields in ields in ields in ields in ields in R RRRReduced Til lage: P educedTil lage: P educed Tillage: P educed Tillage: P educed Tillage: Proper Management roper Management roperManagement roperManagement roperManagement Selecting good hybrids, planting on time, minimizing crop pests, and properly supplying nutrient needs are among essentials outlines by Ohio researcher. C resulting from high residues may slow plant growth early in the season, requiring weed control to be extended for up to an additional two weeks. Otherwise, growers risk having weeds compete with crops for water, sunlight and nutrients. High residues may also delay insect emergence, necessitating a good insect management program. Use of genetic materials is also effective in minimizing crop disease and insect problems. Crop rotations are also very effective. In addition to minimizing insect and disease problems, rotations allow use of a broader array of herbicides in combating weeds. Drainage. Reduced-till usually results in more water availability for a crop during the growing season. Lower soil temperatures mean less evaporation early in the season. Therefore, adequate water drainage is important if the soil is to dry early enough to ensure proper planting dates. Drainage is additionally important to ensure that the soil does not stay saturated for long periods after planting, which can result in seedling loss due to decay, disease, and insect damage. Nutrient management Proper nutrient management is one of the most critical areas under reduced-till Table 1. Benefits of deep fertility in producing high-yield cor n crops for growers in Nebraska and Illinois. Soil depth Schmit, Nebraska Warsaw, Illinois (inches) Phosphate Potassium Phosphate Potassium lbs/A lbs/A 0-6 200 500 107 284 6-12 108 451 31 142 12-18 21 452 6 150 Yield 311 bu/A 338 bu/A
Fluid Journal 1996-1998