- Increasing or maintaing soil organic matter
Increasing organic matter with cover crops and conservation agriculture
1) The Netherlands Case Study - increasing or maintaining soil organic matterThe RECARE researchers tested the effectiveness of various measures to increase or maintain soil organic matter. The main experiment involved grass undersowing in maize. Other experiments included the use a manure separator that differentiates between crops and fields with different soil quality and the application of humic acid.
|Grass undersowing in maize|
- Grass undersowing in maize fields is expected to result in 0.5% extra soil organic matter (SOM) after 30 years, and also a little more production of grass in years with grass cropping. But since the measure was only started in 2014, the result is still unknown. Conversations with four farmers revealed that the SOM content has remained stable or slightly increased, and that the bearing capacity of the soil has improved.
- Average nitrate concentration in the upper groundwater in the area fluctuated around the EU-standard of 50 mg/l: in 2014 and 2017 it was above and in 2005 and 2016 below the standard.
- Farmers experienced variable results from grass undersowing, depending strongly on the weather, with good growth of the grass cover in wet years, but competition for water with the maize crop and no grass growth in dry years. Farmers frequently experienced poor grass cover.
- Drawbacks of the measure mentioned by farmers are that the undersowing may cause damage to the standing maize crop and in the headlands of the fields and that the sowing is a difficult task since it needs to be done at the right places and in the right period. It is difficult to perform in small parcels, and the weed control is more difficult.
- Farmers also indicate that grass undersowing is not effective in a grain maize crop, where only the maize cobs are harvested and the rest of the plant is frittered, thereby suffocating the undersown grass.
- Grass undersowing was evaluated by farmers and residents to foster regulating ecosystem services, namely the increase of the buffer function for organic matter and nitrogen and the bearing capacity of the soil. Also, cultural ecosystem services were found to be improved when fields remain green after the harvest of the maize crop, instead of showing brown stubble.
- However, the provisioning ecosystem services that were foreseen as a result of this measure (increase in feed crop yield and groundwater production) were not mentioned by the farmers as a benefit.
Further details about this experiment can be found in the fact sheet HERE (NL) and in the project report HERE
2) Italy Case Study - increasing organic matter with cover crops and conservation agricultureThe Italian researchers tested the effectiveness of continuous soil cover and conservation agriculture practices to increase organic matter content. They compared untreated soil compared with cover crop and conservation agriculture management systems.
|Increasing organic matter content through long-term sustainable agriculture systems|
Experimental results showed significant differences in crop production between treatments, with lower average yields in CA (5.4 Mg ha-1) than in CC (7.9 Mg ha-1) and CV (8.5 Mg ha-1). Continuous soil cover in CA and CC determined the soil-water balance through increased evapotranspiration and reduced percolation (-30%) relative to CV. On the other hand, CC and CV tillage operations significantly affected NO3-N concentrations, with higher soil solution concentrations in tilled (CV = 74.6 mg l-1; CC = 58.1 mg l-1) than in untilled (CA = 14.0 mg l-1) systems. Model results emphasised that SLM practices responded differently in the short and long 30 terms due to initial inertia to C changes and lower N2O fluxes, followed by higher SOC sequestration, and increased N2O emissions. These results demand time–dependent studies that weigh agro-environmental benefits provided by SLM practices against management alternatives to find a suitable compromise for stakeholders.
Further details about this experiment can be found in this project report HERE.
Pituello, C., Dal Ferro, N., Francioso, O., Simonetti, G., Berti, A., Piccoli, I., Pisi, A. and Morari, F., 2018. Effects of biochar on the dynamics of aggregate stability in clay and sandy loam soils. European Journal of Soil Science, 69(5), pp.827-842. https://doi.org/10.1111/ejss.12676
Chiara Pituello, Nicola Dal Ferro, Gianluca Simonetti, Antonio Berti, Francesco Morari (2015) Nano to macro pore structure changes induced by long-term residue management in three different soils. Ecosystems and Environment, Vol 217, 1 February 2016, Pages 49–58 doi:10.1016/j.agee.2015.10.029