Crop Comments: More money spent on lime may mean less spent on equipment repairs

Let’s flash back to 1966 and our family’s Greene County, NY, hillside farm where my dad wanted to purchase a new tractor. He was told he should expect to pay $100 per horsepower. He bought a new green 70-hp diesel tractor for about $7,000; he also bought a 250-gallon fuel tank and filled it up with 20-cent diesel. Good hybrid seed corn cost about $15/bag. He also had ag lime delivered and spread for $10/ton.

At present, two growers I work with recently both told me that new tractors typically cost about $1,000/hp. Non-GMO seed corn was priced at $225/bag. GMO seed corn is about $325/bag. Of late, fertilizer prices have varied wildly (mostly due to geopolitical messes) but they’re still many times higher than they were 60 years ago. Ag lime increased in price also, to about $30/ton delivered; add another $10 for spreading. Lime prices went up 200%.

Diesel (thanks to the Iran war) delivered to the farm runs about $6.50/gallon – an increase of 3,150%! And non-GMO seed corn increased by over 1,200% in that time!

Of the inputs just listed, the only one that hasn’t kept pace with (or surpassed) inflation is ag lime. Let’s accept the idea that higher yields per acre minimize the acreage that one must harvest in order to yield a certain targeted total tonnage. Thus, it’s a no-brainer that improving yield per acre reduces tractor hours (and repairs), as well as worker hours. It takes a lot more equipment time – and human time – to harvest 200 acres yielding three tons of dry matter (DM) per acre than harvesting 100 acres yielding six tons DM/acre. Total harvest is the same in both scenarios.

I apologize for repeating the yield-enhancing benefits of applying proper amounts of ag lime – amounts determined by soil test results. The stunning cost of these non-lime inputs causes deep-thinking growers to capitalize on the least expensive input to optimize the performance of more expensive inputs.

With huge ongoing geopolitical uncertainty in the world – particularly relating to fertilizer ingredient costs – not liming when soil tests indicate the need to do so is a bad idea. Failure to soil test, to determine lime needs, is just as bad an idea. With a soil pH of 7.0, phosphorus utilization is 100% – a figure which is halved when pH plunges below 6.0. When soil testing, use a lab that gives base saturation percentages (BSPs). A BSP of less than 10% for magnesium will indicate the need for a dolomitic (hi-mag) lime rather than high-calcium lime. BSP is also necessary to determine the balance existing between different soil nutrients.

Some folks believe that if fertilizer price drops a fair amount, reduced efficiency of soil amendment utilization – associated with lowered pH – is an acceptable trade-off. Folks thinking that way forget the benefit of lime as a provider of calcium and magnesium, in addition to its trait as a pH regulator. Plant nutrients, once rendered unavailable, are just as useless to the targeted plants whether they cost $500/ton or $1,000/ton. I refer to my own crop nutrient availability demonstration, conducted during my service as a field crops Extension agent in the mid-1970s.

Working with a cooperating farmer in Otsego County, NY, I divided a gently sloping upland field into three equal parcels. Soil test results recommended four tons of 70% ENV (effective neutralizing value) hi-cal lime/acre. The pH was in the mid-5s. A commercial fertilizer blend of 300 lbs./acre of 15-15-15 analysis (donated by the local farmers’ co-op) would take care of the nitrogen, phosphate and potash needs.

Under the guidance of Cornell’s Agronomy Department, I varied the lime application rate. They said that if I applied half the recommended lime rate on a corn planting, I could expect 75% of the yield increase associated with full lime application. One parcel received 4 tons/acre of lime, one parcel received 2 tons/acre and one parcel received zero lime. The corn piece with zero fertilizer yielded 11 tons/acre of 35% DM silage. The two-ton lime recipient yielded 17 tons silage/acre. The four-ton recipient yielded 19 tons silage/acre. Those professors’ yield forecasts were spot on. They cautioned me that the short-changed corn parcels should get the rest of what they were owed, lime-wise, in the next couple years.

Let me now attempt to couple field crop production with climatology. We know that tillage tends to increase carbon dioxide emissions from the soil. It does so by introducing oxygen to soil, which then reacts with organic matter (58% carbon), liberating CO2, our planet’s most prevalent greenhouse gas (GHG). Here’s what happens next:

Solar radiation hits Earth’s surface. But the more GHGs that are in the upper atmosphere, the more sun energy stays trapped closer to the planet rather than deflecting back into space. Oceans cover about three-quarters of Earth’s surface, absorbing the vast majority of that trapped solar radiation heat. Such extra energy forces water to evaporate, but this water doesn’t go straight, vertically, up into our atmosphere. Water vapor rises from ocean’s surface in a spiral fashion. The more this extra trapped solar energy hits the water – and stays – the higher the resulting sea surface temperature (SST) becomes, compliments of GHGs.

Higher SSTs predispose us to higher wind velocities. When sustained surface winds in this spiral hit 74 mph, that weather event earns the title “hurricane.” It’s not much of a stretch to say that lime applications indirectly reduce land needing to be tilled. At some calculable point, less tillage means tractors experience less wear and tear, requiring fewer repairs. The associated reduction in fieldwork (including fuel consumption), in turn, also reduces CO2 emissions. This, consequentially, helps reduce the severity of tropical storms.

It’s a stretch, but think about it when TV meteorologists start naming weather systems this autumn.

by Paris Reidhead