To study role of gypsum and corn cobs in linkage of fractions in cracking soils. Three soils (Al-Diwaniya , Al-Wihda and college of Agriculture / Abu Ghraib) were chosen for this study . They were treated with two levels of gypsum (0.5 and 1) % with one level (4%) of corn cobs . In this experiment , 2 kg of each studied soil were treated with same levels of corn cobs and gypsum above and incubated at 30 + 2 °C for 90 days and 80% relative moisture content at 33 kpa. And then the soils were sieved with 1 mm sieve to measured the x-ray diffractions . The results showed :
The intensity of clay minerals peaks which treated with gypsum and corn cobs were decreased comparing with control sample. We believed that the gypsum should be facculated on clay minerals surfaces and mask them to appear clearly , and suggested that the gypsum was played an important role in conjugated of soil particles. Results of X-ray diffractions showed that there was no evidence of interaction between organic matter (corn cobs) and clay mineral inter layers.