4TH International Congress on Technology - Engineering & SCIENCE - Kuala Lumpur - Malaysia (2017-08-05)

Soil Nutrient Availability as Affected by Long- Term Tillage and Mineral Fertilization
The use of conservation tillage for crops production worldwide has markedly increased over recent years. Nutrient distribution, especially phosphorus, under no-till (NT) compared with conventional tillage (CT) has been studied. However, little is known about other nutrients availability and distribution. This study was conducted to assess the long term effects (+20 years) of tillage practices (NT and CT) and mineral fertilizations (N and P) on soil nutrients availability and distribution. The experimental site is a long-term maize-soybean rotation established in 1992 on a deep clay loam soil of the St-Blaise series (Dark Grey Gleysol) in eastern Canada. The experimental design is a split plot with NT and CT assigned to main plots and nine combinations of three P (0, [P0], 17.5 [P17.5], and 35 [P35] kg P ha−1) and three N (0, 80, and 160 kg N ha−1) additions assigned to subplots. Soil samples were collected at various periods and analyzed for several parameters (N, P, K, Ca, Mg, Fe, Mn, Cu, Zn, and Cd). Results showed greater organic and inorganic phosphorus concentrations under NT in the surface layer (0-5 cm) compared to the deep layer (5 – 20 cm) inducing a P stratification. Greater organic C and total N were also found in the 0-15 cm of NT compared to CT. Higher exchangeable K was observed under NT compared to CT probably as a result of K released by crop residues not incorporated in the soil. No significant effects were observed for other nutrients and heavy metals contents. Tillage affects the soil fertility status soil under crop rotation systems and may alter nutrients availability.
Noura Ziadi, Antoine Karam