عنوان مقاله [English]
Many researchers in agricultural ecosystems consider the multiple cropping as the most important factor for increasing the diversity of cultures (Vandermeer, 1992). Increasing of crops diversity through intercropping can be effective to improve the functions and ecosystem services. One of the main functions of multiple cropping systems is the weeds control and increasing yield crop (Bulson et al., 1997). Other functions of multiple cropping is included higher nutrient uptake efficiency compared with monoculture systems (Chowdhury and Rosari, 1994)
Material and methods
To study the effects of intercropping on weeds control and nutrient uptake of nitrogen and phosphorus, experimental research was performed as strip split plot based on randomized complete block design at farm of ferdowsi university of Mashhad in the growing season of 2013-2014.
Experimental treatments were included weed factor at 2 levels and also different planting patterns of intercropping of Corn, Soybean and Marshmallow at the 7 levels. For evaluating of weeds diversity was used diversity index of Shannon- viewer (waite, 2000). To evaluate the advantage of intercropping in terms of nitrogen and phosphorus uptake, we used land equivalent ratio for nitrogen and phosphorus uptake.
Result and discussion
The results showed that the highest density of weeds in different planting patterns was observed in sole cropping of soybean (46.7 plat per m2) and the minimum number of weeds was observed in intercropping Maize + Soybean + Marshmallow with 37.6 plants per square meter. The highest amount of the Shannon-Weaver diversity index was calculated in the intercropping of Maize + Soybean + Marshmallow (1.56) and the lowest diversity was obtained in soybean monoculture systems (1.42). The results showed that the planting pattern had no significant effect on weed species richness. LER for nitrogen uptake (LERn) in the intercropping of Maize, Soybean and Marshmallow was more than one that indicating the advantage of intercropping compared with sole cropping of species.
The results showed that intercropping of Maize and Soybean was most profitable with LER for nitrogen uptake by 1.12 unit under weeds control condition. While in the presence of weeds, intercropping Maize + Soybean + Marshmallow with 1.257 unit showed the highest land equivalent ratio of nitrogen compared to others. Land equivalent ratio for phosphorus uptake (LERp) in the intercropping of all species was greater than one under absence and presence of weeds conditions. In other words, intercropping of Corn, Soybean and Marshmallow had higher nutrient use efficiency than sole cropping of species.
The most Land equivalent ratio for phosphorus uptake was achieved from intercropping of Maize + Soybean and intercropping of Maize + Soybean + Marshmallow in both conditions of weed control and without weed control. According to the findings of this study can be summarized that different intercropping patterns caused to reduction of weed density and dry weight and also increasing of nitrogen and phosphorus uptake efficiency in comparison with sole cropping of species and finally intercropping could be provided the higher plants yield.