Studies on ammonia-treated straw. II. Fixation of ammonia in treated straw by spraying with acids

Abstract

Ammonia-treated barley straw (NH 3 straw) was sprayed with either formic, acetic or phosphoric acid immediately after opening the stack in order to capture the excess ammonia. The amount of acid applied was estimated to neutralize 100% of the ammonia added to the straw (30 kg NH 3/t straw). After spraying with acid the straw was stored in plastic bags for about 8 weeks at room temperature (15–20° C). When bags of NH 3 straw treated with acids were opened, there was very little smell of ammonia whereas there was a very strong smell from the bag of NH 3 straw without acid added. The nitrogen content of the straw (g/100 g DM) was for untreated straw, 0.88, NH 3 straw without acid, 2.50, and NH 3 straw with added formic acid, 3.49, acetic acid, 3.81, and phosphoric acid, 2.27. The digestibility of organic matter determined in sheep was 47.3, 60.5, 59.0, 60.4 and 51.3 following the same order as above. It is concluded that spraying NH 3 straw with organic acids effectively reduces the loss of ammonia and increases the nitrogen content of the straw. Another advantage of this is that the air pollution with ammonia which may occur in the barn when the straw is not well aired is effectively prevented. Spraying with organic acids had no negative effect on the digestibility of the straw. The nitrogen supply and the digestibility of nitrogen in the animal seemed to be markedly improved.