Buckwheat fertilizer guidelines

Nitrogen (N) fertilization is an important management practice for optimum production of buckwheat. Nitrogen fertilizer guidelines can be based either on the results of the soil NO₃^--N test or the consideration of the combination of expected yield, previous crop, and soil organic matter content. The soil NO₃^--N test is appropriate for western Minnesota (see Figure 1). When the soil NO₃^--N test is used, the fertilizer N guidelines are calculated as follows:

N_rec = (0.0458) (EY) - STN_{(0-24 in.)} - N_Pc

Where:

EY = expected yield (lb./acre)

STN = nitrate-nitrogen (NO₃^--N) measured to a depth of 24 in. (lb./acre)

N_pc = amount of N supplied by the previous legume crop (lb./acre).

Table 1 summarizes these N credits.

Table 2 lists the N fertilizer guidelines for production situations without a soilNO₃^--N test.

For most production situations, the N fertilizers should be broadcast and incorporated before planting. Apply the N fertilizer  in either dry or liquid form. There is no research to document that one form is superior to the other.

Therefore, all sources of N are equal if properly applied.

*Add 20 pounds of N per acre to the listed credits if the third or fourth cutting wasn’t harvested.

Table 1 lists N credits for various legume crops that might precede barley in a crop rotation. Use these credits for the N_pc factor in situations where the soil nitrate test is used.

*Low = less than 3.0%; medium and high = 3.0% or more.

Use these recommendations for buckwheat in situations when the soil NO₃^--N test isn’t used.

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.

Table 3 summarizes guidelines for using phosphate fertilizer for buckwheat production. Use one of the following equations if you want a phosphate guideline for a specific soil test and a specific expected yield:

• Recommended P₂O₅ = [0.0275 - (0.0014) (Bray P in ppm)] (Expected yield)

• Recommended P₂O₅ = [0.0275 - (0.0017) (Olsen P in ppm)] (Expected yield)

Table 4 shows suggestions for potash use for buckwheat production. Use the following equation if you want a potash guideline for a specific expected yield:

Recommended K₂O = [0.0358 - (0.023) (Soil test K in ppm)] (Expected yield)

CAUTION! Do not apply any fertilizer in contact with buckwheat seed at planting.