EFFECT OF ORGANIC AND INORGANIC FERTILIZATION ON AVAILABILITY OF SOME NUTRIENTS AND SOIL ORGANIC MATTER QUALITY AFTER WHEAT AND CORN CROP ROTATION

Two field studies were conducted at the experimental farm of Sakha Agric. Res. Station to evaluate the impact of composted rice straw, town refuse and their mixture with urea on the availability of NPK nutrients and some soil organic matter fraction and its quality after wheat (Sakha 94) followed by corn (Giza 352) cropping sequence.
The obtained results showed that the tested soil characteristics were affected due to the applied composts as follows:
1.   The obtained results gave significant increases in N, P and K availability under wheat and corn plant but the application of composted rice straw was more effective for increasing available N, P and K in soil in the 2^nd season (after corn), while composted town refuse given an opposite trend.
2.   Light fraction, microbial biomass carbon and polysaccharides increased with increasing application rates especially in the 1^st season (after wheat).
3.   The obtained data show that, raise of application rate of composted material (T₄ & T₇) increased the total carbon (OC%), the percent of humic acid carbon (C_HA) and fulvic acid carbon (CFA) of the total carbon. However, there was significant changes in C_HA/C_FA and C_HA + C_FA /humin carbon (C_hum) ratio but decreased the percent of Chum of the total carbon especially in the 2^nd season. On the other hand, there was no significant changes in E₄/E₆ ratios.
4.   The total acidity and functional groups of obtained humic acid was increased with increasing application rate.