Plant cover : good for fauna…and goods for farmers!7 December 2015
Plant cover or CIPAN* are temporary crops, planted during the several months that separate two commercial crops.
The agronomic interest of plant cover no longer needs to be proved: it allows nitrogen in the soil to be trapped, thus avoiding it being washed out by the rain. Experiments carried out for the last ten years in Alsace have proved that a vegetation cover traps on average 30 UN per T of MS/ha**, and up to 90 UN for the highest performing vegetation covers! Farmers can thus save significant amounts of fertilizer.
Plant covers also have other advantages: they improve the fertility of the soil by bringing in organic matter; their roots do hard “work” and improve the structure of the soil; lastly they combat erosion and mitigate slaking crust*** phenomena on the surface of loamy soil.
Plant cover also supplies refuge areas for fauna during the end of summer, autumn and winter, when soil on agricultural parcels is generally bare. It also is a key source of food for animals during these trying seasons.
In the framework of the Common Agricultural Policy aimed at greening, farmers are asked to plant plant cover in between commercial crop periods to receive the full amount of subsidies. Just another reason to turn a regulatory constraint into an agronomic asset and give a helping hand to fauna in our Alsatian country sides!
For the 2015 – 2016, campaign, the Alsace Region Chamber of Agriculture is currently carrying out an agronomic experiment on plant cover in the framework of the LIFE+ ALISTER programme. This trial aims at comparing several plant covers that are sold commercially. They were selected according to several different criteria, such as resistance to winter frost of species making up the plant cover mixture as well as their nutritive interest for the European Hamster. Various parameters will be studied: development speed and plant cover rate in the parcel, behaviour after soil cultivation by a strip-till machine, etc.
Composition of Chlorofiltre Biomix (a commercial mixture): black oats, rye, purple vetch, hairy vetch, daikon radish, Egyptian clover, crimson clover, Indian mustard, phacelia and flax.
The second picture is a mixture of black oats and crimson clover
*CIPAN: Nitrate-fixing intermediate crops
** 30 units of nitrogen per tonne of dry matter per hectare. In other words, one tonne of dry extract of vegetation cover on one hectare contains 30 kg of nitrogen!
*** Slaking crust is this crust formed on loamy soil after heavy rainfall. This thin crust prevents water and air from circulating and blocks young plantlets that have just germinated. It is impermeable and accelerates runoff and erosion when it starts raining again.