Effect of tillage and nitrogen application regime on : some physical properties and distribution of micronutrients in calcareous soil

الملخص EN

Tillage and nitrogen (N) management practices have profound effects on the variations in plant nutrients and other physical properties of surface and subsurface soil layers.

The study included field experiment established in 2002, at Maryout Experimental station where its soil is calcareous.

The aim of the study was to evaluate the effect of three tillage systems [no–tillage (NT), chisel plowing (CP), and moldboard plowing (MP) with two nitrogen rates (0 and 45 kg / fed.)], the latter was added in three doses, on some physical properties of soil and the distributions of micronutrients in different soil surface layers, (0-10, 10-20 and 20-30 cm).

The results showed that soil bulk density was significantly different between tillage systems and N fertilizer rates.

Soil bulk density decreased for all tillage systems compared with no- tillage, at the three depths.

Also, it was found that the penetration resistance decreased for all treatments and increased with increasing of soil depth.

The maximum values were obtained in no tillage and unfertilized treatments, however the minimum value was associated with moldboard plow and 45-kg N / fed treatment regardless of N doses.

The main effect of tillage or nitrogen doses on soil aggregates TA% was significant, however, the interaction effect between them was not significant.

For example, aggregation over both sites and all N doses were 52.07%, 38.57% and 30.57% and the mean weight diameter were 0.26, 0.17 and 0.13 mm for NT, CP and MP, respectively. Total aggregation for NT were 48.8, 51.10, 53.30 and 55.10%, for CP were 29.50, 40.00, 43.10 and 41.70%, and for MP were 28.50, 30.60, 32.00 and 31.20% for zero, two, three and four N doses, respectively.

Nitrogen fertilization had little effect on nutrient distributions, most dramatic changes occurred within the 0-10 cm depth, due to tillage methods where soil under NT had lower content of Fe and Cu and greater content of Zn and Mn than under CP and MP