Behavior of selenium calcareous soil, treated with humic acid
2006
El-Ghannam, Mussttafa M. | El-Ghazouli, Muhammad M.
A greenhouse experiment was conducted in 2005/2006 during winter. A surface calcareous soil (0-20 cm) as growth medium for faba bean (Vicia faba, cv. Giza 2) was used to study the behaviour of selenium (Se) in calcareous soils treated with humic acid (HA). The humic acid was applied, before sowing and moistened at field capacity with distilled water for two weeks, at rates of 0, 100, 250, 500 and 1000 mg kg. 1 soil. Selenium was added at rates of 0, 1, 2, 4 and 8 mg kg. 1 soil as sodium selenate (Na2SeO4). Increasing selenium levels decreased the dry matter yield and showed a negative correlation with the dry matter yield of bean plants. HA increased dry matter production and showed positive correlation with the yield. Se resulted in a positive significant increase in Se concentration in plant while, HA decreased it. Se-uptake by bean plants was progressively increased with increasing rate of Se addition. It was slightly affected with i ncreasing rates of humic acid application. Se concentration and its uptake by bean plants decreased with increasing selenium application and its rate. There was no clear trend for P-uptake by bean plants with humic acid. K-concentration increased by adding Se at 4 mg kg. 1 and k-uptake decreased with Se addition. Humic acid addition increased potassium concentration and uptake by bean plants. The N2-ase activity of bean plants was increased with increasing the levels of selenium and humic acid addition. The number and dry weight of nodules were positively affected with adding selenium and humic acid. Increasing selenium levels up to 2 mg kg. 1 soil, increased CO2-evolution from the soil then decreased it up to 8 mg kg. 1 soil, CO2-evolution increased gradually with increasing humic acid application rate.
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