The effects of poultry, swine and cattle manure on lettuce yield, quality and groundwater contamination

Abstract

The performance and yield of lettuce grown in soil amended with swine manure, poultry manure, cattle manure or slow release artificial fertilizer were analyzed. The soil was amended with these fertilizers according to the practice used by the Maltese Farmer. This was done by planting 20 iceberg lettuce seedlings for each treatment mentioned above. Another 20 seedlings were planted into pots containing soil with no fertilizer treatment where set as a control. These were placed in a greenhouse and were harvested after 50 days. During the growing season the width and height of the plant was measured on a 1 day interval. A drainage plate was placed beneath each pot in order to collect the leachate for the analysis of NO3 -, electrical conductivity, pH and volume of leachate on a weekly basis. The results indicated that in terms of fresh mass, width of the lettuce head and height of the plant, lettuce performed best in soil amended with poultry manure (289.2g, S.D ±52.9, n= 20; 35.4cm, S.D ±2.15, n=20; 17.25cm, S.D ±1.29, n=20). This was followed by lettuce grown in soil amended with swine manure (229.4g, S.D ±35.8, n= 20; 28.5cm, S.D ±2.8, n=20; 15.3cm, S.D ±1.0, n=20), cattle manure (139.4g, S.D ±70.3, n= 20; 24.0cm, S.D ±4.2, n=20; 13.4cm, S.D ±2.9, n=20) and artificial fertilizer (123.7g, S.D ±19.9, n= 20; 22.0cm, S.D ±1.3, n=20; 10.8cm, S.D ±1.1, n=20). The poorest growth and yield was obtained in lettuce grown in the control (30.0g, S.D ±4.0, n= 20; 16.4cm, S.D ±1.3, n=20; 7.7cm, S.D ±0.86, n=20) where no treatment was applied in the soil. The leachate from each pot was collected to check which manure causes the most negative impacts in the ground water bodies of the Maltese Islands. The results indicated that lettuce grown in cattle manure had the highest negative impacts in terms of salinity and potential nitrate leaching (139.6mg). This was followed by lettuce grown in soil amended with poultry manure (109.5mg), swine manure (70.4mg), artificial fertilizer (13.1mg) and finally the control (7.0mg).