Application of Compost to Different Texture Soils: Effect on Soil Properties and Productivity of Lettuce Crop

The application of composted organic wastes to soil can be used for conserving soil organic matter, reclaiming degraded soils and supplying plants with nutrients. Two greenhouse experiments were carried out to evaluate the addition of compost on chemical and physical properties of soils. Four different texture soils were used: Sandy soil (S1), Silty loam soil (S2), Clay loam soil (S3) (33.2 O.C. g.kg(-1)) and Clay loam soil (S4) (14.8 O.C. g.kg(-1)) cultivated with lettuce (Lactuca sativa L.) in the Bahia Blanca region, Argentina. The application of compost had a significant effect on lettuce productivity and nutrient uptake by the crop in three of the four soil types; showing a positive effect on the dry weight, number, length and width of the leaves. The applied dose (40 Mg ha(-1)) modified the chemical composition of the plants: those grown in soil with added compost showed higher concentrations of nutrients than those grown in control soils. In clay loam soil (S3) no difference were found in plant productivity between treatments with and without application of compost. With respect to soil properties changes, the application of compost affected the soil pH in variable way; increased organic carbon, total nitrogen and available phosphorus. The addition of compost lowered bulk density in soils S2 and S4; increased the percentage of macropores and mesopores in S2; diminished content of mesopores and increased content of micropores at S3 and S4. The variations on chemical and physical soil properties demonstrate the benefits of compost addition, even in a short period of time.