¹- Net Energy for Lactation = Energy available after subtracting digestive and metabolic losses
²- Acid Detergent Fiber = Low values mean more digestible
³- Neutral Detergent Fiber = Low values mean cows can eat more
Mono (lbs./acre): 30-50
Mix (lbs./acre): 20-40
Forage (lbs./acre): 80-120
Aerial (lbs./acre): 20-60
The most efficient time to harvest small grain cereals for hay is at early-milk stage. This allows for the greatest compromise between forage yield and quality (quality would be greatest at the late-boot stage). To help speed up drying, a crimper is recommended when harvesting in the late-boot stage
But some soil scientists and microbiologists are sceptical of a quick microbial fix. “Biofertilisers” like these have had mixed success, depending on the soil and environment in which they are applied, says Tolu Mafa-Attoye, an environmental microbiology graduate student at the University of Guelph in Canada. In one field study of wheat, for example, inoculating the crops with beneficial microbes enhanced growth of the plants but only resulted in slightly greater yields. Unknowns abound, Mafa-Attoye’s Guelph colleagues wrote in February in Frontiers in Sustainable Food Systems – such as whether the microbes will negatively affect the soil ecology or be outcompeted by native microbes.
In that vein, since 2019 the company Pivot Bio has marketed a microbial product called Pivot Bio Proven that, they say, forms a symbiosis with crops’ roots after an inoculant is poured in the furrows where corn seeds are planted. (The company plans to release similar products for sorghum, wheat, barley and rice.) The microbes spoon-feed nitrogen a little at a time in exchange for sugars leaked by the plant, reducing the need for synthetic fertiliser, says Karsten Temme, chief executive of Pivot Bio.
When plant roots don’t take up all the nutrients from fertiliser, the greenhouse gas N2O is released (Credit: E. Verhoeven et al/California Agriculture 2017/Knowable Magazine)
But despite its important contribution to climate change, N2O emissions have largely been ignored in climate policies. And the gas continues to accumulate. A 2020 review of nitrous oxide sources and sinks found that emissions rose 30% in the last four decades and are exceeding all but the highest potential emissions scenarios described by the IPCC. Agricultural soil – especially because of the globe’s heavy use of synthetic nitrogen fertiliser – is the principal culprit.
There’s really a gold mine living in the soil – Isai Salas-González
Steven Hall, a biogeochemist at Iowa State University, is now testing the product in large, dumpster-sized containers with corn growing in them. Researchers apply the inoculant, along with different amounts of synthetic fertiliser, to the soil and measure corn yields, nitrous oxide production and how much nitrate leaches from the base of the containers. Though results of the trial are not yet out, Hall says there’s “good initial support” for the hypothesis that the microbes reduce the need for fertiliser, thereby reducing nitrous oxide emissions.
Yet molecule for molecule, N2O is about 300 times as potent as carbon dioxide at heating the atmosphere. And like CO2, it is long-lived, spending an average of 114 years in the sky before disintegrating. It also depletes the ozone layer. In all, the climate impact of laughing gas is no joke. Scientists at the Intergovernmental Panel on Climate Change (IPCC) have estimated that nitrous oxide comprises roughly 6% of greenhouse gas emissions, and about three-quarters of those N2O emissions come from agriculture.
Temme says that company scientists created the inoculant by isolating a strain of the bacterium Kosakonia sacchari that already had nitrogen-fixing capabilities in its genome, although the genes in question were not naturally active under field conditions. Using gene editing technology, the scientists were able to reactivate a set of 18 genes so the bacterium makes the enzyme nitrogenase even in the presence of synthetic fertiliser. “We coax them to start making this enzyme,” Temme says.
Microbes in the soil break ammonia down through a series of reactions, releasing N2O in the process, which can be measured in the field (Credit: Getty Images)
Today, scientists are looking at several ways to treat the soil or adjust farming practices to cut back on N2O production.