EFFECTS OF POULTRY MANURE AND MINERAL FERTILIZERS ON THE YIELD OF CROPS

Experiments at the Experimental Station of the Agricultural University of Padova, Italy (45-degrees 21'N, 11-degrees 58' E) during 1985-89 evaluated poultry manure as a fertilizer. Two levels of fertilization (medium and high), using different mixtures of poultry manure and mineral fertilizers were compared with a non-fertilized control. The fertilization treatments were repeated each year on the same plots. All the crops tested responded strongly to fertilization, giving the following increases in yield (expressed as a percentage of the maximum yields): 30% for potato (Solanum tuberosum L.), 19% for sugarbeet (Beta vulgaris L. var. saccharifera L.), 82% for onion (Allium cepa L.), 85% for tomato (Lycopersicon esculentum Mill.) and 64% for spinach (Spinacia oleracea L.). The most effective fertilization formula varied with crop and year of cultivation. All the tested fertilization treatments had a similar effect on potato and onion, whereas the highest yields of tomato and spinach were obtained with a mixed fertilization at the highest rate of nutrients.