Effects of cereal-legume cropping systems on soil fertility in extreme weather conditions

Intercropping is often regarded as a promising strategy for improving soil fertility and nutrient availability, particularly under extreme weather conditions. One of the most common intercropping combinations involves cereals and legumes, known for their potential positive effects on soil properties. Therefore, this study examined the short-term impact of intercropping lentil-oat (80% - 20% of the pure stands seeding rate) and field peas with barley (70% - 30% of the pure stands seeding rate) on soil chemical properties in comparison to their respective pure stands. For this purpose, two experiments were conducted at the experimental fields of the Institute of Field and Vegetable Crops in Novi Sad, Serbia, during 2024, a year characterized by record high temperatures and severe drought. Soil samples were analyzed for total carbon (C), total nitrogen (N), available phosphorus (AL-P205), and available potassium (AL-K20) at depths of 0-30 cm and 30-60 cm. A randomized complete block design was employed, and soil samples were collected at the end of the growing season. Analysis of variance revealed significant differences in soil nutrient concentrations among treatments. Duncan's multiple range test further distinguished the performance of intercropped and pure stand treatments. The results indicated that intercropping influenced soil nutrient distribution, particularly in deeper soil layers. In the lentil-oat trial, oat pure stand had the highest total C content at both depths, whereas intercropping resulted in intermediate values. In the field pea-barley trial, barley pure stand showed higher total C in the topsoil, while field peas retained more C in the subsoil. Total N content was generally higher in lentil-oat intercropping than in pure stands, as well as in field pea-barley intercropping and field peas pure stand compared to barley alone. This effect was especially noticeable in deeper soil layers, suggesting that intercropping helps reduce nitrogen depletion. Phosphorus availability was highest under intercropping in the lentil-oat system and under barley pure stand in the field pea-barley system, with statistically significant differences observed in deeper layer. Potassium levels were highest in pure stand lentil and barley in their respective trials, while intercropping resulted in slightly lower values. This study confirms that intercropping systems enhance nitrogen and phosphorus availability while influencing carbon sequestration and potassium distribution in the soil profile, particularly in response to extreme climatic conditions. However, since this research was conducted as a one-year trial, long-term studies are necessary to fully evaluate the sustained benefits of intercropping compared to pure stand cropping systems.