by Steve Wagner

“I tell folks, ‘Look, I’m human. I’m just like you. Some of us try to work and farm at the same time,’” says Dwane Miller, Penn State Education Extension Instructor. “The year 2015 was a challenging year for us to make hay. I tried to make people guess what date I finished making first-cutting hay on our farm. That was July 24. And I marketed that as mixed hay. Anybody know why?”

“I think there would be a little fiber to it,” offered fellow Extension Educator Jeff Graybill, “but I guess you would want that in dry hay.” Beginning with the basics, Graybill mentioned soil fertility and what are often their accompanying concepts — barrel and stave, or the weakness link — ones that have been recognized in many crops, but “your yield is limited by the most limiting nutrient or the most limiting factor that’s out there.” Starting with a soil test, knowing your soils, knowing your fertility program, and perhaps using tissue testing, you must determine what is to be replenished.

Graybill notes that there are three phases of fertility management in forages. You could consider it a no-till crop once it is established. “The soil profile footnotes that it is difficult to raise the pH and the nutrient level if you’re not doing tillage.” So, one to three years before you go into hay, and if you’re doing a crop such as corn, or tilling for hay, there are given situations that deserve forethought before you undertake anything. Often when growing corn, it calls for a high rate of manure to be added. Also it is a time when you could be doing some tillage, and that is the time you should be thinking of building up the soil nutrient level to get ready for that extended period when you will be in a hay crop. Checking Penn State’s Agronomy Facts 31-A: Soil Fertility Management for Forage Crops (Pre-establishment), a worthy quote cuts to the chase. ‘Crops vary in their sensitivity to soil pH. Generally, alfalfa is the most sensitive forage crop, followed by the other legumes and then by the grasses. …With nitrogen fertilizer applied, soil pH has little or no effect on the field of alfalfa. With no nitrogen applied, however, there is a very dramatic alfalfa yield increase as soil pH is increased. Thus, it boils down to adding lime to maintain the proper soil pH or adding nitrogen fertilizer. Adding limestone is much more economical than adding nitrogen fertilizer. A typical requirement of two tons of lime for 3 or 4 years would cost about $10 a year, compared to 250 pounds of nitrogen required every year, which would cost about $60 per year.’

“If you didn’t know, the pH is a measure of hydrogen ions that are in the soil solution,” Graybill says. “Hydrogen has a positive charge which causes the acidity. The other thing about pH…7 is neutral when there is no hydrogen in the soil solution; above 7 is not hydrogen. It is Hydroxyl (OH) which contains oxygen bonded to hydrogen. It is also a logarithmic scale. So a pH of 6 has 10 times the amount of acidity of a pH 7. A pH 5 would have 100 times the acidity.” Thus ends the chemistry lesson. Obviously, different crops have different requirements, different ranges where they were originally bred and developed or discovered. “Most of the common crop species that we grow,” Graybill notes, “are in that 6 to 7 range.”

Graybill referenced Joe McGann, a corn specialist for Penn State who said ‘The biggest limiting factor to corn in Pennsylvania was not fertility; it was pH because at low pH aluminum can come into the soil solution and it can become toxic.’ This is true of any crop species because as the pH becomes low, things like aluminum fosters reduced availability of nutrients. It is not as apropos for the soil microbes that thrive, and deficiencies in basic nutrients like calcium and magnesium soon become evident. Calcium is involved in big soil structure. “The only way to know where we are,” Graybill says, “is to take a good representative soil test.”

Generally, in most crops, starter fertilizers are a benefit in the planting season. “If you’re planting…if it’s a fall seeding or a later spring seeding…generally starter fertilizers tend to be more expensive. If you are using a starter fertilizer you want a high phosphorous content, and for grasses, you want nitrogen in there.” Another Penn State recommendation is that nitrogen plus potash should be kept less than about 60 pounds. If it is higher than that, salts that are in the potash and the nitrogen can burn those developing roots. “As far as grasses,” Graybill says, “in the seeding or the establishment a little bit of nitrogen at seeding is in order. Generally, we’re using anywhere from 40 to 50 pounds of nitrogen per ton of hay that we’re expecting, dry grass hay.” That might be 20 to 40 pounds at seeding, and then another 30 to 50 later in the season. That amount can be increased as yield potential goes up in the second year.