With fertiliser demand increasing is it time to look at alternatives?

The Food and Agriculture Organisation’s annual fertiliser report, forecasts that world demand for nitrogen, phosphorus, and potassium will grow on average by 1.5, 2.2, and 2.4 percent respectively from 2015 to 2020 . With demand rising so rapidly, producers are being encouraged to use fertilisers efficiently, and to work with their available natural resources, particular their soils, to ensure sustainable and economically viable crop production. 

According to biological farming expert, Gary Zimmer, for producers to truly realise their soil potential they need to prioritise soil health.

“If your soil is healthy it’ll unlock the available nutrients for crops to uptake,” says Gary. He adds that biological farming is all about balancing the chemical, physical and biological properties to achieve naturally productive soils.

“Soil fertility shouldn’t be solely reliant on nitrogen; producers should be looking at the complete soil health picture. There are over 17 elements that are needed to grow a healthy, vigorous and high yielding crop.

“For example, as well as N, P and K, plants need calcium to support soil and plant health. A soil high in calcium will have more oxygen, drain freely and support the breakdown of soil organic matter.”

Gary adds that most nutrients required by plants are not typically readily available, and therefore soil microorganisms play a huge role in delivering nutrients to plants.

“When microorganisms decompose organic matter, they use carbon and nutrients in the organic matter for growth and release excess nutrients into the soil where they can be taken up by the plant.

“Therefore, a lack of carbon in the soil can present an extremely challenging environment for plants to establish and grow. By adding complex sources of carbon to the soil it’ll stimulate the activity and growth of soil microbes,” explains Gary.

He adds that for the last five years, he’s used a high carbon molasses based fertiliser, in the form of Boost, to provide a readily available source of energy for soil microbes.

“By prioritising soil health, I’ve seen fantastic results in terms of plant growth and soil fertility, across one million acres,” says Gary.

Soils structure

He adds that it is not just nutrients which play a role in crop establishment and development, but also the physical properties of the soil.

“Bad soil structure not only results in nutrient wastage through leaching and compaction, it also leads to poor root penetration and drainage problems resulting in poor access to nutrients,” explains Gary.

“Improving soil structure by managing cultivations and not disturbing the middle zone of the soil profile where possible, will help to maintain microbiological activity and increase the uptake of nutrients.”

He also adds that cover crops can help promote a better soil structure and reduce nutrient leaching by protecting the soil’s surface.

Carbon to Nitrogen ratio (C: N)

Gary adds that if farmers are looking to improve soil health, and increase their organic matter content, it’s important they understand their soil carbon to nitrogen ratio.

“The carbon to nitrogen ratio directly impacts residue decomposition and nitrogen cycling in soils. The optimum C:N ratio is around 24 parts carbon to one part nitrogen.

“Therefore, one of the key principles of biological farming is to manage the decay of organic materials and use rotations to introduce plant diversity to ensure sufficient carbon and nitrogen supplies.

“Legumes such as clover, peas and vetch will fix nitrogen in the soil, however they are reliant on a sufficient carbon being available in the soil to ensure microorganisms remain active,” explains Gary.

Role of carbon in soils

“Soil organic carbon (SOC) is essential to help feed soil microbes and the release of nutrients for plant uptake.

“A direct effect of poor SOC can result in less diversity of microorganisms leading to slower plant decomposition,” says Gary.

“Although there isn’t an on-farm test available to measure SOC, it’s important to manage carbon reserves though sustainable practises such as biological farming techniques.

“There are two main ways to build soil carbon. Firstly, by reducing losses to the atmosphere and secondly by adding carbon back into the soil where possible.

“This can be done by though the careful management of cultivations, planting cover crops, managing plant residues, spreading manures or compost, or by adding a liquid carbon-based fertiliser.

“By maximising the efficiency of nitrogen uptake through the soil, by ensuring sufficient carbon, we can become more efficient and reduce our reliance on inputs,” concludes Gary.

Case study: Tim Parton, Brewood Park Farm, Staffordshire

Farm manager Tim Parton has been using biological techniques for the last ten years to enhance the productivity of his soils and minimise inputs.

“Having sufficient carbon in the soils to feed soil microbes is really important.

“I regularly apply Boost from QLF Agronomy, a molasses based liquid carbon-based fertiliser, to feed soil microbes and enhance the biology of my soils. It’s greatly improved residue decomposition which has not only reduced disease pressures but has also prevented nitrogen lock up.

“Ultimately, it’s a combination of biological practises that have helped me to nurture my soils and improve the quality of my crops,” says Tim.