Effects of farmyard manure on soil organic carbon stock, the pattern of fertility build-up, and plant growth in 'Mallika' mango (Mangifera indica L.)

A field experiment was conducted on mango (Mangifera indica L.) to study the effects of farmyard manure (FYM) on soil organic carbon (SOC) content and on the build-up of fertility over three growing seasons (2006-2007, 2007-2008, and 2008-2009) at Bhubaneswar, Orissa, India. Five treatments, including the application of FYM at 5.0 kg plant(-1), 7.5 kg plant(-1), or 10.0 kg plant(-1), the recommended dose of a chemical fertiliser (RDF; N:P:K=75:20:60), and a non-fertilised control, were evaluated in a randomised block design. The results indicated that SOC contents increased significantly in the FYM-treated plots. The highest SOC density (554 g m(-2)) and stock (5.55 Mg ha(-1)) were recorded in the treatment with FYM at 10 kg plant(-1). The rate of increase in SOC density was highest (193 g m(-2) year(-1)) with FYM at 10 kg plant(-1), and lowest in the untreated control (15 g m(-2) year(-1)). Regular addition of FYM had a positive effect on the build-up of soil fertility. However, the greatest increases in soil N, P, K contents were in the 7.5 kg plant(-1) FYM treatment (means = 319.9, 19.1, and 270.8 kg ha(-1) for N, P, K, respectively). Farmyard manure significantly influenced the growth parameters of mango trees over the three seasons. There was a positive and linear relationship between increasing rates of application of FYM and trunk cross-sectional area.