Effect of Rice-Duck co-Cultivation on Rice Yield, Water Productivity and Weed Control in Different Cultivation Systems

Rice-duck cultivation is an integrated farming technology, which could increase rice production, grain quality and ecological sustainability in paddy fields. One of the main strategies in sustainable agriculture is the use of optimal cultivation systems in agricultural systems which could be increased the range of adaptation of rice to flooding depth and degree of moisture control. Rice-duck cultivation could be affective to weed control as well as reducing environmental pollution which caused by herbicides and providing the development of environmentally friendly agriculture. It should be noted that traditional and conventional cultivation systems have been faced with problems such as permanent flooding of paddy fields, soil erosion, resistance to pests and pathogens and weeds to chemical pesticides, and environmental pollution. Moreover, they require a lot of labor and water, and high energy, which has increased the need to pay attention to new approach. Studies have showed that the application of effective methods in water productivity, including SRI due to improved irrigation management in the field in terms decreased drainage water, permeability and the consequences of conventional cultivation and increasing soil fertility (duck) can significantly increase the water productivity. The aim of this study was to investigate the effect of duck application and weed control in different planting systems on yield and abundance of dominant weeds under field conditions.

The experiment was conducted as a split plot factorial in a randomized complete block design with three replications during two years of 2017-2018 and 2018-2019 at Guilan University. Treatments included three different cultivation systems (conventional, improved, and SRI) as the main factor, and factorial combination of two duck density (un-use and 750 No ha-1) and three weed control (control (un-weed control), once and twice of weed control) as the sub factor. The experiment had three replications and the length of each plot was 4.5 meters and the width was 4 meters. In order to carry out the experiment, first plowing in the land to a depth of 20 to 25 cm with a rotator and paddling with a tiller was done according to the custom of the farmers of the region. In all plots, 80% of the recommended fertilizer was applied in SRI system after deducting the values of cow.

The results showed that abundance and dry biomass of weeds (Umbrella sedge, Barnyard grass, Knot weed and Arrow leaf) were significant in terms of planting system. In all planting systems, 750 ducks ha-1, once and twice weed control, caused complete loss of ovaries, Umbrella sedge, Barnyard grass, Knot weed, and Arrow leaf due to ducks' non-use conditions. 750 ducks ha-1 compared to un-use duck in conventional, improved and SRI planting systems increased grain yield of 21.61, 20.80 and 30.84%, respectively. Also, the application of 750 ducks ha-1 in compared to the conditions of un-used of duck in the cultivation systems of conventional, improved and SRI, increased by 34.80, 33.01, and 38.69% of water productivity, respectively, while there was no significant difference between different levels of weed control in the 750 ducks ha-1 in terms of water productivity.

In general, duck increased plant growth, improved power of rice and finally increased rice yield by proper weed control in the field with muddy water and beak, as well as adding rubbish to the paddy field. According to the results of this study, probably do once the initial hand weeding to control dominant weeds in SRI rice cultivation system with 750 ducks ha-1 to improve rice production systems and to increase water productivity in fields of Guilan province is appropriate.