Dried edible bean fertilizer recommendations

Optimum yields of this crop depend on efficiently using nitrogen (N) fertilizers.

You can base N use guidelines on the results of a soil NO₃^--N test or considering the combination of expected yield, previous crop and soil organic matter content.

The soil NO₃^--N test is appropriate for western Minnesota (Figure 1), but isn’t recommended for sandy soils, even in western Minnesota.

Recommended N = (0.05) (EY) - STN_{(0-24 in.)} - N_Pc

Where:

• EY = Expected yield, in pounds per acre.

• STN = Nitrate-nitrogen (NO₃^--N) measured to a depth of 24 inches, in pounds per acre.

• N_pc = amount of N supplied by the previous legume crop, in pounds per acre.

Table 1 summarizes these N credits.

Table 1 shows credits for various legume crops that might precede the edible bean crop in the rotation. Use these credits when using the soil nitrate test.

Table 2 summarizes N fertilizer guidelines for situations where the soil NO₃^--N test isn’t used. These suggestions are appropriate for edible bean production on fine-textured soils.

When grown on sandy soils under irrigation, use the standard guideline of 120 pounds of N per acre. If edible beans follow alfalfa on sandy soils, an N credit of 70 pounds of N per acre for the alfalfa crop is suggested.

Table 2 shows recommendations for edible bean grown on non-irrigated fine-textured soil and when a soil NO₃^--N test isn’t used.

*Low = Less than 3.0%; Medium and high = 3.0% or more

Crops in Group 1:

Alsike clover, birdsfoot trefoil, grass/legume hay, grass legume pasture, fallow and red clover.

Crops in Group 2:

Barley, buckwheat, canola, corn, grass hay, grass pasture, oat, potato, rye, sorghum-sudan, sugarbeet, sunflower, sweet corn, triticale and wheat.

Crops not considered previous crops

Because of the high potential for diseases, if edible bean should follow soybeans, edible bean, peas and other crops of edible bean, these crops aren’t considered previous crops in the rotation.

Nitrogen application timing

Timing the nitrogen application is an important consideration for edible bean production.

To minimize damage from white mold, it’s important to keep the canopy open as much as possible. The canopy may be closed at flowering if all the N fertilizer is applied before planting.

This is why split applications of fertilizer N are suggested, especially for sandy soils. Research shows delayed applications of fertilizer N don’t reduce yields.

You can make the first application approximately two weeks after planting, and the second application as late as it’s practical for field equipment. Time the second application so the equipment doesn’t damage the crop.

Table 3 summarizes current phosphate guidelines. Guidelines for potash use are in Table 4. The guidelines in these tables are for both broadcast and banded applications.

There’s no research suggesting one placement is more efficient than the other. Recent research suggests these immobile nutrients, when applied in a band near the seed at planting, produce substantial yield increases.

Banded applications are an excellent option when suggested rates are low.

Use one of the following equations if you want a phosphate guideline for a specific soil test and a specific expected yield.

• Recommended P₂O₅ = [0.0231 - (0.0011) (Bray P in ppm)] (Expected yield)
• Recommended P₂O₅  = [0.0231 - (0.0014) (Olsen P in ppm)] (Expected yield)

In table 4 use the following equation if you want a potash guideline for a specific soil test and a specific expected yield:

Recommended K₂O = [0.0346 - (0.00042) (Soil test K in ppm)] (Expected yield)

Past research with the edible bean crop has indicated that zinc (Zn) is the only micronutrient that may be needed in a fertilizer program. Table 5 lists Zinc suggestions for both starter and broadcast application.

Research has shown no other nutrients are needed in a fertilizer program.

For the Zinc soil test, zinc was extracted by the diethylentriamene pentaacetate (DTPA) procedure.