No-Tillers whose fields were ravaged by drought last year will face some crucial decisions this spring as they investigate nutrient levels in their fields
In farm ground where runoff or leaching was minimized, there could be residual fertilizer available for this growing season. But weather, soil types, application methods, removal rates and many other factors will complicate the picture, says retired Virginia Tech fertility specialist Mark Alley.
“We have to have balanced fertility in order to get the root systems growing well and to get our crops producing the most crop per unit of water that we have available,” Alley told attendees at the 2013 National No-Tillage Conference.
The variables most farmers know this spring are last year’s yields, soil-sample results, rainfall and temperatures since crop maturity, as well as the crops to be grown in 2013. To find out what nutrients are left in fields, estimating the rates of nutrient removal and uptake is the next step, says Alley, a consultant to Koch Agronomic Services.
For corn yielding 150 bushels an acre, removal rates for nitrogen are 112 pounds, while it’s 66 pounds for phosphorus, 43.5 pounds for potassium, 8 pounds for magnesium and 16 pounds for sulfur.
“We can compare those removals to what we applied last year and you get some idea if you’re putting something into the bank or pulling it out,” Alley says.
Estimating nutrient uptake — in this case, corn — is another piece of the puzzle. Nitrogen uptake for 150-bushel…