Started in 1843, Rothamsted Broadbalk is the world’s longest-running agricultural experiment. Established to test the long-term effects of inorganic fertilisers and organic fertilisers on the yield of winter wheat and soil health.
Recently covered by Farmers Weekly, results have shown that adding farmyard manure increased soil organic matter, which enhances soil oxygen levels. This improvement in oxygen availability boots nitrogen use efficiency.
Organic carbon flow through soil is crucial for good soil structure, oxygen availability, nitrogen use, and microbial activity. Well-managed soils can better link the fates of carbon, nitrogen, and oxygen, which enhances the productivity of arable systems.
Benefits of Farmyard Manure in Summary:
- Increased soil carbon stocks.
- More connected pore networks.
- Reduced gaseous nitrogen losses.
- Higher soil oxygenation.
- Improved nitrogen use efficiency.
- Enhanced farm performance.
Comparison with Inorganic Fertilisers:
Soils treated with farmyard manure have more extensive and connected pore networks than those treated with inorganic fertilisers. These improved pore networks lead to better oxygenation and reduced nitrogen losses. Soils with low organic inputs have poorly connected pores, reduced oxygen levels, and higher nitrogen losses as nitrous oxide, a potent greenhouse gas.
Microbial Activity:
Well-oxygenated soils, resulting from the use of farmyard manure, encourage beneficial microbial populations. These beneficial microbes use oxygen for respiration and contribute positively to soil health and nitrogen use efficiency.
In poorly structured, anoxic soils, microbes use alternative respiration methods, leading to nutrient depletion and increased emissions of harmful gases like nitrous oxide and hydrogen sulphide.
Management Implications:
Appropriate soil management, which ensures good oxygen levels, can promote beneficial microbial populations. Farmers can achieve better nitrogen use efficiency and environmental benefits by maintaining well-oxygenated soils with organic matter inputs like farmyard manure. Prof. Andrew Neal emphasises the importance of connected soil pores, smaller than a human hair, in maintaining soil health by improving water holding capacity, nutrient delivery, and positive biological activity.
