Soil and fertilizer for buckwheat

Buckwheat will produce a better crop on low fertility soils than cereal grains. It will produce a crop on newly cleared land, drained marshland, or on other marginal land. Buckwheat has a higher tolerance to soil acidity than the cereal grains.

Buckwheat does require a soil that is easily pene-trated by its fine roots, and has good aeration under ground. Hard degraded soil will water stress the plants. Hardpan or crusting cause the seedling roots to suffocate. On the other hand, excessive fertility often leads to viny growth with low yields.

Buckwheat yields do not respond to high applications of fertilizer, especially nitrogen. A buckwheat crop that yields 20 bushels per acre will remove approximately 25 lb of N, 15 lb of P20, and 20 lb of K2O from the soil.

General Fertilizer Recommendations

Highly fertilized rotation land (corn, cabbage, peas) 
lb/ac pH>6 pH<6
N none none
P2O5 0-15 20
K2O none none
 		  
Managed land with medium fertility (small grains)
lb/ac pH>6 pH<6
N 0-15 0-20
P2O5 25 30
K2O 0-15 0-20
 
Poor soils, abandoned land, old pastures. 
lb/ac pH>6 pH<6
N 15-25 25-35
P2O5 35 40
K2O 20-25 30-35
 
Nitrogen mineralization is often rapid when buckwheat is growing fastest, so additional nitrogen is often unnecessary. Too much nitrogen crates weed pressure, encourages excessive vegetative growth, causes lodging, decreases grain yield. Excess nitrogen responses are especially noticeable when phosphorus is deficient.

Buckwheat often shows little response to superphosphate, but it is the most effective user of rock phosphate. Because buckwheat uses mostly insoluble phosphorous sources, the phosphorus values reported in a soil test result may not accurately reflect the amount of phosphorus available to the buckwheat crop. An important exception is in potato rotations in Maine, where 40 to 100 lb/ac phosphate fertilizer had a marked effect.

As with any crop, fertilizer application should be based on soil test results. Applications more than 40 lb/ac of actual N (nitrogen) and K20 (potash) and 100 lb/ac actual of P205 (phosphate) are uneconomical.

Buckwheat will tolerate more soil acidity than most crops and can grow successfully on soils with a pH between 6.0 and 6.5. It will produce reasonably well at pH between 5.4 and 6.0 if adequate P205 is provided. Lime to a pH of at least 5.4

Buckwheat can effectively remove the available nutrients from the soil, so a soil test after buckwheat is important to prevent nutrient deficiency in the following crop. Phosphorus and calcium  are especially worth watching.