The use of sorbents on the basis of humic acids to reduce ammonia levels in stable environment

Laboratory testing of sorption properties of humic substances, which were e xposed to increased ammonia levels from 0 to 300 mg/g in a system, showed a highly significant (P less than or equal to 0.01) increase of ammonia leve ls up to the value of 27.1 +/- 1.32 mg/g of ground humic substances. The in crease of ammonia level in the system to 400 and 500 mg/g had not any signi ficant effect on its concentration in the humic substances (27.8 +/- 208 an d 28.7 +/- 1.73 mg/g). The results of laboratory testing of ammonia binding to humic substances are shown in Fig. 1, In a series of experiments perfor med in experimental stables of the institute and aimed at testing the use o f humic acids for the reduction of free ammonia level, 3% of sodium humate were administered in the ration for pigs in two subsequent periods (I and I I). At the same time, nitrogen balance (the amount of nitrogen intake by fe ed and excretion by faeces and urine) was monitored. In another two periods (III and IV) 1 kg of ground humic substances was applied twice a day on th e floor of experimental stable, i.e. 150 g/m(2)/day. Eight pigs were includ ed in the experiment, housed in balance cages, four in one cage in two iden tical separated stables. The pigs received feed mixture composed of 68.3% o f wheat, 20.0% of barley, 10.0% of soya extracted meal and a mineral supple ment. The average daily intake of feed mixture was 1.16, 1.27, 2.00 and 2.2 0 kg/animal/day in periods I, II, III and IV, respectively. The levels of f ree ammonia were recorded daily at 7 a.m. and 2.30 p.m. in both stables thr oughout the whole experimental period. Air temperature and relative humidit y were measured in the stables as well as outdoor temperature and atmospher ic pressure (Tab. I). Significantly lower (P less than or equal to 0.05) av erage levels of free ammonia (6.9 +/- 1.58 ppm) were found in period I in t he stable;where sodium humate was administered, compared with the stable wi thout humate administration (10.4 +/- 3.35 ppm). However, this result was n ot confirmed in period II. Nonsignificantly lower levels of free ammonia (6 .4 +/- 1.28 ppm) were found in the stable without humate administration com pared with the stable with sodium humate administration (7.6 +/- 2.00 ppm). Variations in average levels of free ammonia in both stables during period I and II are shown in Fig. 2 and 3. Recording of nitrogen balance (period I and II) revealed that pigs of the control group had daily nitrogen intake 34.9 +/- 3.51 g and those of the experimental group 33.8 +/- 4.84 g. Suppl ementation of feed mixture with 3% of sodium humate resulted in the experim ental group in a decrease of daily intake of nitrogen by 3.2% (Tab. II). Da ily output of nitrogen by faeces was significantly higher (P less than or e qual to 0.01) in the experimental group of pigs with administration of 5.35 +/- 1.86 g/animal/day of sodium humate (15.8% of N) compared with 3.69 +/- 0.68 g/animal/day (10.6% of N administered) in the control group. Daily ex cretion of nitrogen by urine was significantly lower (P I 0.01) in the expe rimental group reaching 11.2 +/-. 2.92 g/animal/day (33.1% of N administere d) than in the control group reaching 14.6 +/- 1.53 g/animal/day (41.9% of N administered) (Tab. II). In period III significantly lower (P less than o r equal to 0.05) levels of free ammonia (6.5 +/- 1.12 ppm) were found in th e stable where ground humic substances were applied on the floor compared w ith the control stable (11.0 +/- 4.43 ppm). Like in period IV, significantl y lower (P I 0.01) average levels of free ammonia (7.2 +/- 2.44 ppm) were r ecorded in the experimental stable compared with the control one (12.0 +/- 2.89 ppm). Variations of the average levels of free ammonia in both stables during per iods III and IV are shown in Figs. 4 and 5.