Two field experiments were carried out at Sakha Agriculture Research
Station Farm during 2002 and 2003 summer seasons using soybean (Glycine max)
variety Giza 111 to investigate the effect of phosphogypsum (PG) as a source of
posphorus and some nutrients, superphosphate (P) and potassium (K) on soybean
yields, nutrient status in soil and plants. Split plot design was used in four replicates.
The main plots were assigned by four treatments of 1- without PG and P (check
treatment), 2-application of 2 ton PG/fed., 3- application of 15 kg P20S fed" as
superphosphate 15% (P), and 4- application of PG + P (2 ton PG+ 15 kg P20slfed.).
The subplots were assigned by three potassium (K) levels of 1- without potassium
(Ko), 2- application of 24 kg K20 fed' (K,) as potassium sulphate 48%, and 3-
application of 48 kg K20 fed" (K2).
The results can be summarized as follow:
Phosphogypsum application led to increase soybean seeds and straw
yields: while PG + P gave the highest oil yield kg fed".
, Potassium application at the rate of 48 kg K20 fed" observed a decrease in
oil yield kg fed". Addition of PG + P led to 38.77% increase in protein yield kg fed" in
the first season. In the second season addition of P alone led to 22.51% increase in
protein yield kg fed". PG caused a detected increase in soybean nodules number
and nodules dry weight comparing with the other treatments. PG application slightly
decreased soil pH. On the other hand a slight increase in soil EC due to PG
application was obtained, PG application increased the residual available N, P and K
in the soil.