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2022 Midwest Vegetable Guide

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Soil Fertility and Nutrient Management 18 Midwest Veg Guide 2022 only 20 to 50 percent of the total N before planting. Apply the remaining N with regular drip irrigation at 5 to 10 pounds of N per week until the total recommended for the season has been applied. K may also be applied through drip irrigation if the crop needs more than has been applied to the soil before planting. If you apply only part of the recommended N before planting, apply the remainder as a sidedressing when the plants are still young, or apply N through fertigation before and during the period of rapid crop growth. Early sidedress applications are especially important with crops such as sweet corn, broccoli, and cabbage. The total N applied during the growing season (broadcast, plus banded, plus transplant starter, plus sidedressed, plus fertigated) should equal the recommended N rate. Applying more than the recommended rate of N may be necessary when there are leaching rains. Transplanted crops often respond to a small amount of water- soluble fertilizer in the transplanting water. Special fertilizer grades (such as 14-28-14, 10-52-10, 23-21-17) are used at a rate of 3 pounds per 50 gallons of water. The high-P liquid 10-34-0 can also be used at the rate of 2 quarts per 50 gallons of water. Apply starter solutions at 8 ounces per plant. If dry weather is prevalent, irrigate after setting the plants. Fertilizer Rates per Linear Bed Foot You can apply fertilizer in a band while shaping beds or laying plastic. You can also apply it dissolved through irrigation water and delivered by drip tape to the base of the plants. In these systems, it is helpful to calculate the fertilizer rate per linear bed foot (LBF) based on the fertilizer rate per acre. To do so, you will need to know: • Bed spacing (BS): distance in feet between bed centers • Fertilizer rate in lb./A (RatePerA) Use this equation to determine the fertilizer rate in pounds per LBF: (RatePerA X BS) / 43,560 = RatePerLBF Example: Bed spacing (BS) = 5 ft. between centers of beds Fertilizer rate in lb./A (RatePerA) = 100 lbs./A (100 X 5) / 43,560 = 0.0115 lb./LBF For a crop on six 100-foot beds, there would 600 LBF to fertilize. The amount of fertilizer needed to supply 100 lbs./A would be: 600 LBF X 0.0115 lb./LBF= 6.9 lbs. The Rate per Linear Bed Foot for Various Bed Spacings and Rates table provides conversion of lb./A to lb./LBF for a number of bed spacings and fertilizer rates. Rate per Linear Bed Foot for Various Bed Spacings and Rates Bed Spacing (ft) Linear Bed Feet (LBF) in 1 Acre Fertilizer Rate (lbs./A) 20 40 60 80 100 120 Fertilizer Rate (lb./LBF) 3 14,520 0.0014 0.0028 0.0041 0.0055 0.0069 0.0083 4 10,890 0.0018 0.0037 0.0055 0.0073 0.0092 0.011 5 8,712 0.0023 0.0046 0.0069 0.0092 0.0115 0.0138 6 7,260 0.0028 0.0055 0.0083 0.011 0.0138 0.0165 7 6,222 0.0032 0.0064 0.0096 0.0129 0.0161 0.0193 8 5,445 0.0037 0.0073 0.011 0.0147 0.0184 0.022 9 4,840 0.0041 0.0083 0.0124 0.0165 0.0207 0.0248 10 4,356 0.0046 0.0092 0.0138 0.0184 0.023 0.0275 Soil pH and Adjustment Soil pH describes whether the soil solution is acidic or alkaline. The native pH of Midwest soils varies from quite acidic (pH 5.0 or lower) to quite alkaline (pH 7.5 or higher). Most vegetable crops prefer a pH range of 6.0-6.8 on mineral soils. On muck soils, a pH of 5.5-5.8 is considered adequate. Vegetables grown under acid soil conditions lack vigor and yield poorly. Acid soils restrict the uptake of nutrients such as P and K. Acid soils also make elements such as aluminum (Al) and manganese (Mn) more available to plants so that the plant may absorb enough to be toxic to the plant. Under severe conditions, visible foliage injury can result from magnesium (Mg) deficiency and/or Mn toxicity. Physiological disorders such as blossom end rot are more common on acid soils. In contrast, when soil pH is high, Mn, B, iron (Fe), and certain other micronutrients become less available for plant uptake. Deficiencies of these micronutrients are most likely to occur on mineral soils with pH greater than 7.4. Lime neutralizes soil acidity and supplies Ca and Mg, elements necessary for plant growth. A soil test determines how much lime you need. Liming may be necessary every few years because soil pH tends to decline over time. The decline is caused by ammonium-releasing N fertilizers, the crop's removal of Ca, and the leaching of Ca and Mg by rain. Soil pH and Plant Nutrients Nitrogen (N) Plants can take up N in the form of ammonium (NH 4 + ) or nitrate (NO 3 - ). In the soil, ammonium is converted into nitrate, and vice versa, by particular sets of microbes. When soil pH is near neutral (pH 7), and the soil is moist and warm, the microbial conversion of ammonium to nitrate (nitrification) is rapid, and crops generally take up nitrate. In acid soils (pH lower than 6), nitrification is slow, and plants will take up a higher percentage of N as ammonium. Soil pH also plays an important role in N loss due to volatilization. Volatilization occurs when N compounds turn

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