growing seasons of 2013-2014 and 2014-2015, in a private farm at El-Salheya El-Gedida City, Ismailia Governorate, Egypt, to investigate the effect of rice straw (RS) as alternative to sandy soil (SS) and drenching applications of potassium humate (K2-HA) at 2 g/l, potassium silicate (K2SiO3) at 5 g/l, and seaweed extract (SWE) at 0.5 g/l on improving growth of sweet pepper (capsicum annuum L.) plants under deficit irrigation every 2 (I2), 3 (I3) and 4 (I4) days in addition to daily irrigation (I1) as control. Plant samples were taken at 90 days after transplanting to record leaf area, shoot fresh and dry weights, in addition to, determination of leaf relative water content (LRWC), concentrations of  N, P, K and Ca. Mean values of drenching applications showed significant increase in the growth parameters ;shoot fresh and dry weights, leaf area, LRWC, as well as, concentrations of  N, P and Ca in the two seasons comparing to untreated control and the best results were due to K2-HA followed by SWE then K2SiO3. The highest concentration of  K was obtained by K2SiO3 followed by K2-HA then SWE. Plants were grown on RS showed significant increase in LRWC comparing to plants were grown on SS. Plants were applied with I2+ K2-HA+ SS showed the highest significant value of shoot fresh weight, shoot dry weight, leaf area, N, P and Ca concentrations followed by I2+SWE+SScomparing to control plants applied with I1+ SS without drenching applications. Plants were grown on RS showed significant increase in growth parameters comparing with control plants but less than those were grown on SS. The best results were achieved by I3 + K2-HA+ RS, I3 + SWE+ RS, I4 + K2-HA+ RS. Plants were grown on rice strawunderI3 irrigation and applied with K2-HA or SWE showed significant increase in N, P and Ca concentrations, while, under I4  irrigation an increase in N and P concentrations was obtained by K2-HA.The highest concentrations of k were observed with plants grown on SS under the highest level of irrigation deficit I4 by K2SiO3.It could be concluded from the present study that rice straw could alleviate the negative effect of low water supply and applications of K2-HA and SWE are recommended for enhancing sweet pepper growth and nutrient elements uptake under water deficit conditions.

Composting technique is considered as one of the environmentlly friendly methods used for recycling the excess residues of rice straw ( RS) and solving the environmental problems of olive pomace (OP) by-product of the olive oil industry. For this purpose, three compost piles were made from mainly rice straw, different ratios of olive pomace and some agricultural wastes viz. tomato hallum, banana residues and farmyard manure to evaluate the stability and maturity of composted materials during 90-day composting period. The first pile (A) was made of 60% RS+10% OP+10% tomato hallum+10% banana residues+10% farmyard manure, the second pile (B) wase made of 50% RS +20% OP+10% tomato hallum+ 10% banana residues+ 10% farmyard manure while the  third pile (C) was made from 40% RS + 30% OP10% tomato hallum+ 10% banana residues+ 10% farmyard manure. Representative compost samples were taken after 15, 30, 45, 60 and 90 days of the composting process. The results revealed that slight increase in temperature occurred through the first 2-3 days of composting to reach  the maximum values at 30 days of composting (thermophilic stage). All the composts showed a more pronounced increase in pH, EC, bulk density and total nitrogen, while total organic carbon significantly declined with composting progress. Consequentially, the C/N ratios became narrowed during composting process where they reached 18.80 for pile C. At maturity stage, the greatest values of humification parameters (Humification index, Humification degree and Humification rate) were obtained by pile C followed by pile B. Meanwhile, the ratio of  NH4+/NO3- as an indicator to nitrification process, Extinction coefficient (E4/E6) as well as CO2 rate decreased gradually to reach the minimum values. Finally, the highest values of germination index (92.22 and 95.39%) were achieved with pile C for cress and barley seeds, respectively