Significance of applied organic manure for minimizing hazardous effects of water salinity and specific anions on some characteristics of a calcareous soil and plants grown thereon

Abstract EN

A green house pot experiment was carried out on a newly reclaimed calcareous sandy loam soil (0-30 cm) having about 22 % CaCO3 at Demo Experimental Farm of Agric.

Fac., El Fayoum Univ.

to study the hazardous effects of the usage of different water salinity levels (i.

e., 250, 600, 1200, 2400 and 4800 mg L-1) as well as the specific effect of anions (i.

e., Cl-, CO32- and SO42-) on some soil and plant characteristics.

The response of the studied soil and the plants grown thereon (elephant grass as a new summer green forage) characteristics to organic manure (organic compost of plant residues) was a matter of concern in this study.

The obtained results showed that there were pronounced adverse effects on the studied soil physio-chemical properties as well as its fertility status (i.

e., bulk density, soil strength, total porosity, hydraulic conductivity, available water content, pore size distribution, organic matter content, pH, ESP and the released available nutrients content in soil) with increasing water salinity levels.

In addition, these negative effects were not only associated with rising water salinity levels but also with the specific effect of anions.

However, the hazardous effect of Na2CO3 salt surpassed both NaCl and Na2SO4 levels due to its destroyer effect on soil aggregates, and consequently the other studied soil properties.

In this concern, the accompanied anions could be categorized according their hazardous effects in an ascending order : CO32- > Cl- > SO42.

The aforementioned hazardous effects of the applied water salinity levels on soil characteristics were extended to the vegetative growth (germination percentage and dry weight) and the nutrients uptake by the grown elephant grass plants, which showed gradual decreases with increasing water salinity levels.

This may be attributed to the adverse effect of the higher soil solution salinity on inhibiting uptake of plant roots for all nutrients.

It was also evident from the obtained data that applied organic compost at a rate 30 m3 / fed led to alleviate many of the adverse effects of the water salinity levels and their specific effects on both the studied soil and plant characteristics.

In general, the applied organic manure increased active organic acids, and hence enhanced the availability of both essential macro- and micronutrients (N, P, K, Fe, Mn, Zn and Cu).

The later case is considered more affective under restrictive conditions of such calcareous soil media; moreover the applied organic manure attained a relatively higher content of these essential nutrients.