COTTON RESPONSE TO ELEMENTAL SULPHUR AND PHOSPHORUS APPLICATIONS UNDER DIFFERENT SOIL MOISTURE DEPLETION LEVELS AT NORTH NILE DELTA

Two field experiments were conducted at Sakha Agric. Res. Station during
two successive seasons 2000 and 2001 to investigate the response of cation crop to
the levels of soil moisture depletion. applications of the elemental sulphur and
phosphorus ar Nann Niie Delta. The 50il of the e epenment wac clayey in texture, non
saline and non alkaline. The design of the experiment was split-split plot during the
two growing seasons. Depletion levels 40% (01). 55% (02) and 70% (0₃) of available
soil moisture were conducted to the main plots. Elemental sulphur rates, zero (S,),
50 (S2) and 100 (S3) kg S fed:' were assigned to sub-plots. Phosphorus fertilizer
rates zero (P,), 15 (P₂) and 30 (P3) kg P20S fed:' were allocated to sub-sub-plots.
The most important results could be summarized as follows:

Irrigation of cotton at 55% depletion (02) produced the highest seed cotton yield
(10.92 and 10.51 kentar fed:') in the 1" and 2^nd season, respectively. Also, plant
height, fruit branches/plant, botts/plant and boll weight were higher under
treatment 02.
Irrigation at low soil moisture depletion (0,) resulted in the highest values of
water aPRlied (3666.3 and 3451.7 m³ fed:'). water consumptive use (2993.8 and
2760.2 m^J fed:') in the 1 SI and 2M seasons, respectively. but decreased water
utilization and water use efficiencies.

Decreasing soil moisture depletion increased P, Fe and Mn concentrations jn
colton leaves and its availability in the soil. while Zn took the opposite trend.

Application of S resulted in a significant increase in seed cotton yield, yield
components, water utilization, and water use efficiency, soil available P, Zn, Fe
and Mn and their content in cotton leaves.
Application of phosphate fertilizer resulted in a significant increase in seed cotton
yield, yield components, water utilization, water use efficiency. soil available P,
Fe and Mn and the concentrations of P and Mn in colton leaves.

Tho combination between 100 kg Sand 30 kg P20~ fed:' and irrigation at 55%
deptetion produced the highest seed cotton yield in the two studied seasons.
An antagonistic relationship was found between P and Zn & Fe and a synergetic
between P and Mn in cotton leaves.