The Yield and Economic Response is Solid (Virtually Guaranteed, Nearly a Sure-Bet etc.)
Wet weather last summer has left many farms with tight forage inventories this spring. Budgets are probably even tighter. Year in and year out, one of the most reliable crop production investments is nitrogen fertilization of grass crops in the spring. Applying 75 to 100 lbs nitrogen per acre at green up increases yields (about 50% more in first cut) and quality (about 4 points higher CP and 3 points lower NDF). The graph below shows Forage Income over the Cost of N fertilizer from a N response trial in Delaware County a few years ago. N application, at recommended rates, gave a significant return even if fertilizer prices are well above what we expect to see this spring.
Cutting Management Critical
Cutting management goes with N fertilization. Early cut grass is highly digestible, and most of you know from experience that cows perform when you feed it. When N is not applied, many are reluctant to cut when grass is at peak quality, deferring to wait for more yield. Fertilized fields have good growth at peak quality, and fields cut early regrow quickly and usually will have a nearly equal second cut 30 days later. N fertilization and aggressive cutting management.
When is the Right Time?
So, when is the right time to begin grass harvest? The chart below shows fiber content (NDF%) and fiber digestibility (NDFD) by the day in May taken from the past 11 years of scissors cut samples in Delaware County. The long term average is for grass to reach the optimum NDF level (50%NDF) for starting grass harvest on May 16,. You will also notice that as the month progresses, fiber digestibility trends down as fiber content goes up. More mature grass has more fiber and that fiber is less digestible, meaning a cow can eat less (fewer pounds) and gets less energy from each pound she eats. Watch the scissor cut reports to see how this year’ crop develops and be ready to begin harvest when the first weather opportunity hits.
Grass needs Sulphur too, so it’s becoming more common to see a little ammonium sulfate (AMS) mixed with urea for grass topdress, especially where there is little or no manure history (manure is an excellent source of Sulphur). Consider a 75% uea-25% AMS blend. Our recommendations are to apply N at green up in the spring (early-mid April, depending on the year) If you’re applying urea this early, you should consider a nitrogen stabilizer to protect your fertilizer investment from wafting off with the breeze, if the application cannot be timed close to a rain fall. Later application also will likely benefit, but the chances of good conditions, rainfall and rapid N uptake, are better then.
When grass has good fertility, first cutting yields are high yielding and of excellent quality. Highly digestible forages have always been a key factor in low cost rations. So in a year with tight margins and tight forage inventories, fertilizing those core grass fields, where aggressive harvest is going to happen, is a sound investment.