On the problem of protecting the base area beneath intermediate manure storage piles on non-permanent sites with bentonite or straw

The suitability of bentonite and straw as materials for protecting the soil against the infiltration of leached nutrients was tested on an intermediate storage pile of cattle manure established during the winter months of 93/94. During the 185-day storage period, 205 g of N-t (68% in the form of NH4+) and 695 g K+/m(3) were leached out of the manure. These nutrients seeped away into the soil, but with increasing depth, the concentrations ofNH(4)(+)-N and K+ in the soil water dropped while those of NO3- rose not to harmful levels. Under the test piles whose base areas had been protected with bentonite, the concentrations of NH4+-N and K+ in the soil water were in all cases significantly lower than under the test piles with straw base or no base protection. Both cations were to a large degree absorbed by the bentonite layer, and thus were readily available for recycling. The N-min content in particular was reduced in the soil beneath the straw layer. One possible explanation for this fact is that nitrogen was reincorporated by microorganisms due to the plentiful supply of carbon.