An environmentally benign and cost-effective technique for reducing bird damage to sprouting soybean seeds

Worldwide, birds are considered to be the most destructive pests of soybean during the sprouting and seedling stages. The spotted dove, Spilopelia chinensis (Scopoli) and occasionally feral pigeon, Columba livia Gmelin (Columbiformes: Columbidae) causes heavy damage in newly sown soybean fields in northeast India. Due to adverse side effects of chemicals on ecosystem and protection of the S. chinensis by laws; use of reflective ribbons and protecting nets are very common practices to prevent the bird damage in soybean. Scarring of birds manually by employing labourers is expensive; while the reflective ribbons provide inadequate protection against the birds. Although protective nets are highly effective, they are expensive and unaffordable for small and marginal farmers, Therefore, to find out a cheaper and environmentally friendlier technique, a series of experiments was conducted on soybean variety 'Bragg' at the entomology farm during the year 2011-2013. Initially, the foraging behavior and feeding preferences of the doves and pigeons were studied under field conditions, and accordingly different sowing times (STs), planting depths (PDs), and temporary physical barriers (TPBs) were employed to protect the sprouting seeds from the damage. Rice and maize straw along with reflective ribbons were used to create TPBs over the sown field. The doves and pigeons preferred feeding on sprouted seeds only up to the green cotyledon stage. However, the seedling damage was observed up to the first trifoliate leaf stage. An inverse relationship was found between the delay in ST and PD with the bird damage. Significantly lower damage (18.5%) was found in treatments consisting of rice straw cover with reflective ribbon (RSCRR). The bird damage varied significantly with different STs, PDs, and TPBs during 2012-2013. Also, the damage varied significantly for treatments with interactions between ST x PD, ST x RSCRR, PD x RSCRR, and ST x PD x RSCRR. The overall results show that, bird damage was significantly reduced (only 3.45% bird damage); when the soybean was sown during mid July at a 4.0-cm PD and temporarily covered with RSCRR. Rice straw being cheaper and readily available biomass can further be re-utilized for composting and other agro-processing techniques. This technique can also be applied in other parts of the world with slight modifications in the ST and PD. (C) 2016 Elsevier B.V. All rights reserved.