We’re six weeks past the date where many crop people in the Northeast – though certainly not all – experienced their first killing frost. This morning at dawn in downtown Hartwick, our remote-sensing thermometer read 25º F. In the last couple weeks, there have been several freezing readings most locations, and those have generally, within a couple days, been counter-balanced by unseasonably warm temperatures. Wikipedia defines “Indian summer” as “a period of unseasonably warm, dry weather that sometimes occurs in autumn in temperate regions of the northern hemisphere. Several references describe a true Indian summer as not occurring until after the first frost, or more specifically the first killing frost.”
A little more research revealed that weather historian William Deedler wrote that Indian summer can be defined as “any spell of warm, quiet, hazy weather that may occur in October or November,” though he noted that he was “surprised to read that Indian summers have been given credit for warm spells as late as December and January.” Deedler also noted that some writers use Indian summer in reference to the weather in only New England, “while others have stated it happens over most of the United States, even along the Pacific coast.”
Quoting Wikipedia again, “Although the exact origins of the term are uncertain, it was perhaps so-called because it was first noted in regions inhabited by Native Americans, or because the natives first described it to Europeans, or it had been based on the warm and hazy conditions in autumn when Native Americans hunted.” Examining this term a little more scientifically, we find that most climatologists agree that an Indian summer is typically caused by a sharp shift in the jet stream from the south to the north. The warm weather may last anywhere from a few days to over a week and may happen multiple times before winter arrives for good.
Indian summer is a good time to feed living crops soluble nutrients (not bare corn stubble) – particularly winter forages. As a few words of review, these include wheat, rye, triticale (a hybrid of the first two), speltz and barley. Soluble nutrients that can be fed to these species include urea (hopefully in protected form), mono-ammonium phosphate, diammonium phosphate and injected liquid manure slurry. These will be taken up and metabolized by these winter forages. Some growers still call them cover crops.
New York field research has found that up to 60 pounds of nitrogen (N) per acre increased spring yields of fall-planted triticale by 43%, on fields without prior spring/summer manure applications. Early plantings and autumn N applications significantly increased the number of tillers, which in turn set the spring yield potential. Even with autumn N applications, most agronomists recommend including sulfur (S), with a 10:1 ratio of N:S. However, bear in mind that rye plants, the tallest of the winter forage species, tend to be more prone to lodging with N rates exceeding 50 lbs./acre in autumn.
Nutrients that can be applied to soils – with or without winter forages – include mined and/or unrefined amendments like ground limestones, rock phosphates, bone meal and some forms of potash. These items are feeding the soil rather than feeding the growing plants directly. These also greatly benefit from the freezing/thawing action of northern soils during winter. Such freezing/thawing seesaw behavior serves to make otherwise bound-up nutrients become more available to crops come spring. This benefit, compliments of Jack Frost, of enhanced soil nutrient availability shows that money spent this autumn on these inputs shows a handsome return on investment at harvest time next growing season.
This freezing/thawing action has been shown to increase the effective neutralizing value (ENV) of ground limestone. Quoting a bulletin from the Minnesota Department of Agriculture: “ENV is the fraction of the material’s CCE that will react with soil acidity in the first year of application. The ENV is calculated by multiplying a liming material’s CCE and its fineness. The CCE analysis consists of determining the combined total of calcium/magnesium carbonate and oxide contained in an ag-lime. CCE is expressed as a percentage of 100% pure calcium carbonate. Pure calcium carbonate is the standard by which all ag-lime chemical purity is compared.”
The punchline to the joke here is that if we can accept that the assist from Jack Frost helps increase the ENV of a liming material, this would mean that – in terms of supporting next year’s crops – we can likely get by applying less lime this autumn than would be required with a spring 2023 application. Another plus would be that, as I write, field conditions in the Northeast are generally pretty passable. I’ve taken quite a few soil samples in the last couple weeks in Otsego County. Who knows what field conditions will be next spring?
We’re certain that liming materials improve the utilization of fertilizer ingredients, particularly P and N. Combine that certainty with the uncertainty of global fertilizer ingredient price volatility. We can conclude that using one input that’s increased 30% in price in the last 30 months (lime) to maximize the utilization efficiency inputs that have increased, on average, 150% (N and P), in that same timeframe, is a no-brainer. Although anhydrous ammonia (FOB Port of New Orleans) priced at $756/ton in November 2021, its price at FOB NOLA on Nov. 3 was $1,040. With all the geopolitical uncertainty in the world – particularly as it relates to fertilizer ingredient costs – not liming when pH indicates that such is necessary is a bad idea.
Not soil testing to determine whether or not lime is needed is just as bad an idea. Be sure to use a lab that gives base saturation percentages (BSP). A BSP for magnesium of less than 10% will indicate the need for a dolomitic (“hi mag”) limestone, rather than a “hi-cal.”