Ecological assessment of the nitrogen budgets of livestock production systems in Ukraine

The nitrogen budgets was modeled on the example of 5 typical Ukrainian livestock farms of different livestock production systems. The relative anthropogenic load of different livestock systems and the efficiency of the use of nutrients in the production of crop and animal products are shown. Input flows of nitrogen (N) — in the fodder for livestock, fertilizers, biofixation, atmospheric deposition, crop residues and output flows with agricultural crop & livestock products were determined. It was established that the efficiency of nitrogen use (NUEfarm) is 21.0–69.9% on the investigated farms, i.e., such amount of soil nutrients and imported feed in nitrogen equivalent was deposited in the sold products, and the rest of N was deposited in by-products (crop residues & manure). The ratio of produced main and by-products in nitrogen equivalent was determined. In crop production, 1.06– 1.11 Mg N of grain is obtained for 1 Mg of N crop residues. In livestock, only 0.15–0.78 Mg N of the main products (milk, meat, wool) are obtained for 1 Mg of manure nitrogen production (nitrogen excretion). According to the level of output of the main products relative to by-products, the livestock systems are in the following ranked order: cattle farming — 0.15 Mg N of milk and live weight gain per 1 Mg manure nitrogen production; pig farming — 0.43 Mg N of live weight gain per 1 Mg N excreted and broiler farming — 0.78 Mg N of live weightgain, respectivel. It was established that the livestock production systems cause a significant anthropogenic load on the surrounding natural environment — intensive soil load (balance from –30.2 to –42.2 kg N/ha/year) and high rates of ammonia and greenhouse gas emissions (NH3, NOx and N2O) from manure management systems and agricultural land (16.3–1456.4 kg/ha/year). It was established that 132.4 kg of NH3, NOx and N2O are emissed for 1 Mg of live weight gain of calves; 7.6 kg of NH3, NOx and N2O per 1 Mg of produced cow’s milk; 30.3 kg of NH3, NOx and N2O per 1 Mg of live weight gain of pigs (on average); 22.2 kg of NH3, NOx and N2O per 1 Mg of live weight gain of broiler chickens; 53.7 kg of NH3, NOx and N2O per 1 Mg of produced live weight and wool of sheep.