Effect of soil texture and bulk density on the leaching of urea fertilizer

الملخص EN

-Urea and water movements are monitored in two soils (sandy and loamy sand).

The sandy soil was packed uniformly in PVC columns at two different bulk densities (1.705 and 1.876 mg/m3).

The loamy sand soil was packed similarly at 1.476 and 1.640 mg/m3.

The ume in the loamy sand soil.

So, to delay the appearance of urea migration in either soil, it may be recommended to relatively compact the soil in a site of urea application during a fertilization process.

Hence, the compaction of soil will reduce the migration of urea that leads to an improving in the ground water quality.

height and diameter of soil column were 0.210 m and 0.086 m, respectively.

Urea solution of 30 g/l was applied at the top of each soil column using a 0.015 m constant pressure head.

An effluent of each column was collected periodically.

The concentration of urea in the effluent was measured colorimetrically.

The concentration distribution of urea in the effluent was described using the computer program of CXTFIT.

The dispersion coefficient, D, and the mean pore water velocity, v, were calculated using the CXTFIT program.

In general, the program described more than 97% of the variations in the effluent concentrations of the urea.

The D ranged between 0.418 to 0.065 m2/day for the low and high bulk densities in the sandy soil, respectively.

The respective variations in v were 8.287 and 2.836 m/day.

In the loamy sandy soil, the D values varied from 0.691 to 0.050 m2/day for the low and high densities, respectively.

The v values of the loamy sandy soil decreased from 8.489 to 3.413 m/day for the low and high bulk density conditions, respectively.

So, increasing the bulk density reduced the dispersion coefficient greatly which resulted in reducing the urea movement.

Effect of the bulk density on the dispersion coefficient was significant with LSD equals 0.126 m2/day.

The soil texture did not affect the mean water pore velocity in both soils.

Also, the soil texture did affect the dispersion coefficient at high bulk density.

However, the dispersion coefficient of both soils differed significantly at the low bulk density.

The urea appeared in the effluent after 0.25 and 0.60 pore volume for the low and high bulk densities, respectively, for the sandy soil.

The respective appearances occurred after 0.25 and 0.50 pore vol-