Modification of fertility by agronomic practices on the soil in Famatina, La Rioja, Argentine

摘要

The study was carried out with garlic (Allium sativum L.) cropped in a sandy loam soil in Famatina, La Rioja Argentine. Strips of soil were used with the following soil treatments: T1, a 2-year period with no fertilizers or manure after one year without cropping; T2, a 2-year period with chemical fertilizers (CF) preceded by garlic.); T3, combined use of CF and 23 t ha-1 of goat feces for a 1-year period preceded by oats (Avena sativa L.); T4 pooled CF and 23 t ha-1 of goat feces for a 2-year period preceded by oats; T5 a 1-year period with CF came after an oat crop of two years; and T6, use of CF following a 2-year period of alfalfa (Medicago sativa L.). Soil samples were taken at planting and at harvest from top soil to 80 cm depth . The PCA ( principal Component Analysis) was used to analyze soil variables. The levels of OM, nitrates, total N, P and K were favored at the T3 and T4 compared to T2. The alfalfa crop showed the lowest pH (6.2) and EC( electrical conductivity) levels which were associated to the highest nitrate contents between 30–80 cm depth . At this soil depth, nitrate contents of T3 and T4 were similar to that of T2 and T5. In the 2nd year of T2, pH changed (from 7.2 to 6.8) and C content (from 0.6 to 0.4 %), and EC increased (1.9 to 2.8 dS m-1).