Soil and Fertilizer for Buckwheat
Buckwheat will produce a better crop than cereal grains on low fertility soils. It will produce a crop on newly cleared land, drained marshland, or on other marginal land. Buckwheat has a higher tolerace of soil acidity than the cereal grains do.
Because of its fine roots, buckwheat does require a soil that is easily penetrated and that has good aeration underground. 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 bu/ac will remove approximately 25 lb of nitrogen, 15 lb of P205, and 20 lb of K20 (potash) from the soil.
General fertilizer recommendations
| pH > 6 | pH < 6 | |
|---|---|---|
| N (lb/ac) | 0 | 0 |
| P2O5 | 0-15 | 20 |
| K2O | 0 | 0 |
| pH > 6 | pH < 6 | |
|---|---|---|
| N (lb/ac) | 0-15 | 0-20 |
| P2O5 | 25 | 30 |
| K2O | 0-15 | 0-20 |
| pH > 6 | pH < 6 | |
|---|---|---|
| N (lb/ac) | 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 unecessary. Too much nitrogen creates weed pressure, encourages excessive vegetative growth, causes lodging, and 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 phosphorus 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 40-100 lb/ac of phosphate fertilizer had a marked effect.
As with any crop, fertilizer application should be based on soil test results. Applications of more than 40 lb/ac of actual nitrogen and K2O and 100 lb/ac of actual P2O5 are uneconomical.
Buckwheat will tolerate more soil acidity than most crops and can grow successfully in soils with a pH between 6.0 and 6.5. It will produce reasonably well at a pH between 5.4 and 6.0 if adequate P2O5 is provided. Lime to a pH of at least 5.4.
Buckwheat can effectively remove the available nutrients from the soil, so it is important to perform a soil test after buckwheat is harvested to prevent nutrient deficiency in the following crop. Phosphorus and calcium are especially worth watching.