nteraction of nutrient resource and crop diversity on resource use efficiency in different cropping systems

Conventional operations in fields، soil and water management are not efficient and loss of and damage to the environment are considerable (Lal، 2000). Crop diversity and understanding the complex interactions between environmental and socioeconomic factors are approaches to make better use of limited resources (Tengberg et al.، 1998). The most diverse ecosystems have a higher production under environment stress conditions compared with ecosystems with low diversity due to the better efficiency in the use of water، radiation and nutrients (Hulugalle & al، 1986; Walker & Ogindo، 2003).

In order to investigate the effects of crop diversity and nutrient source on resource use efficiency، a split plot experiment was conducted based on complete randomized blocks with 3 replications at the Agricultural Research Station، the Ferdowsi University of Mashhad، Iran، during 2006 and 2007. The treatments included manure and chemical fertilizers as the main plots and intercropping of 3 soybean varieties (Williams، Sahar and Gorgan3)، intercropping of 3 Millet species (common millet، foxtail millet and pearl millet)، intercropping of millet، soybean and sesame (Sesamum indicum) and intercropping of millet، sesame، fenugreek (Trigonella foenum-graecum) and ajowan (Trachyspermum ammi) as sub plots.

The results indicated that in the first year، intercropping of 3 Millet species and intercropping of millet، soybean and sesame showed the highest water use efficiency (WUE) based on biological yield. In the second year، intercropping of 3 millet species showed the highest WUE based on biological yield. The highest concentrations of nitrogen، phosphorous and potassium in crop tissues were observed in intercropping of 3 soybean varieties and intercropping of millet، soybean and sesame. In the first year، intercropping of 3 soybean varieties showed the highest nutrient use efficiency (NUE). In the second year، intercropping of 3 soybean varieties، intercropping of millet، soybean and sesame and intercropping of millet، sesame، fenugreek and ajowan showed the highest NUE. In the two years، intercropping of millet، soybean and sesame and intercropping of millet، sesame، fenugreek and ajowan showed the highest nitrogen and phosphorus absorption efficiency (NAE). Intercropping of millet، soybean and sesame showed the highest potassium uptake efficiency. In this study، nutrient resource did not have a significant effect on water and nutrient use efficiency. The research results have indicated that often nitrogen amount and use efficiency in legume and non legume intercropping were higher than monocultures. This indicates the synergist effect in the intercroppings (Vandermeer، 1989; Szumigalski & Van Acker، 2006). In general، the different benefits of diversity and better use of available inputs are obtained by increasing the diversity of crops and proper selection of plants cultivated in intercropping systems and crop rotations in monoculture systems