Mitigation Effect of K-Humate on N, P and K Phytoavailability in Three Different Egyptian Soils under Salinity Stress

    SOIL salinity has several adverse effects on phytoavailability of …...nutrients and plant growth in arid and semi-arid regions. This study investigated the mitigation effect of K-Humate application on the phytoavailability of N, P and K nutrients in three different Egyptian soils; from Kafr El-Sheikh, West Nubaria and South Al-Tahrir under salinity stress condition using Amberlite IRN-150 resin capsules. Representative surface soil samples (0-15 cm) were artificially salinized through equilibrium with four electrolytic solutions having four salinity levels (0, 5, 20 and 40 me/l, SAR= 7) prepared using mixtures of Na₂SO₄ and CaCl₂ salts (S1, S2, S3 and S4, respectively). Soils were then treated with 0, 1, 2 and 3g K-Humate/kg soil under each salinity level. Pots were subjected to drying/rewetting cycles for a period of 60 days then resin capsules were inserted into the soil, incubated for 14 days at soil water FC and phytoavailability of N, P and K were measured (RAQ, g/cm²). Results showed that increasing soil salinity had significantly adverse effects on N-RAQs and P-RAQs. Application of K-Humate significantly increased N-RAQs and P-RAQs up to the rate of 2 g K-Humate/kg soil under each salinity level in the three tested soils. The highest percent increase in N-RAQs and P-AQs were found to be at the highest salinity level S4. While K-RAQs was not significantly affected by increasing soil salinity, it was significantly increased by increasing K-Humate application rate. Further field research is required in diverse plant environments to assess economical feasibility of K-Humate and comparison with other manures and organic fertilizers.