The Effect Of Poultry, Cattle And Swine Manure Applications To Soil On Lettuce Yield And Quality And Ground Water Contamination Potential

This study investigated the effect that poultry, cattle, swine manures, and artificial fertilizer have on the yield and quality of lettuce (Lactucasativa L.). The groundwater contamination potential of these fertilizers when applied to calcareous soil was also studied. Lettuce plants were cultivated in pots containing soil amended with either of the fertilizers together with a no-fertilizer control. The amount of fertilizer applied to soil was in line with that used by the lettuce growers in Malta. The experiment, including 20 replicates for each treatment, was set up in a greenhouse and the crop height, width, fresh and dry mass, root length, sap NO3- and K+, and heavy metal content were monitored. The drain water from the pots was analysed periodically for NO3- content and salinity. The best crop performance was obtained from poultry manure followed by swine manure, cattle manure and artificial fertilizer. Yield from the control soil was poor and also resulted in a crop containing the highest NO3- concentration in the sap. No significant difference was found in sap NO3- concentration in plants grown in soil amended with the fertilizers. The heavy metal content concentration in the plants was not significantly different except for Ni, Mn and Cu. The highest NO3- leaching was shown in the soil amended with manure, especially with that from poultry. Crops grown on cattle manure showed the highest variation in crop mass and also the lowest yield-to-ground water NO3- contamination potential ratio.