Comparative Effect of Poultry Manure, Ash and NPK Fertilizer on Soil Chemical Properties and Trifoliate Yam (Dioscorea dumetorum) Performance in an Alfisol of Southwestern Nigeria

The decline in soil fertility is a fundamental impediment to agricultural growth and food production. This has necessitated the growing search for efficient soil fertility improvement practices. The field experiment was conducted in Akure during the major cropping seasons of 2013 and 2014 to assess the effect of different amendments on the chemical properties of an Alfisol using trifoliate yam (Dioscorea dumetorum) as a test crop. The experiment was laid out in a randomized complete block design with three replications. The treatments were Poultry Manure (PM) at 20tha-1, Wood Ash (WA) at 20tha-1, NPK 15:15:15 at 400kgha- 1 and a Control (CTRL) (no soil amendment). Data collected on soil chemical properties and crop growth and yield performance were subjected to analysis of variance (ANOVA) with the means separated using Duncan Multiple Range Test (DMRT). Results of this study indicated that WA increased the number of leaves, vine length, tuber length and tuber weight of yam and also improved soil pH, OC, N, P, K, Ca and Mg compared with the CTRL (control). NPK did not increase the yield of trifoliate yam but improved the soil nutrient concentrations compared with the CTRL (control). Relative to the control, WA increased the tuber weight by 14% in 2013 and 34% in 2014 respectively. Compared with NPK fertilizer, WA improved tuber yield of trifoliate by 17% in 2013 and 31% in 2014 respectively. Wood Ash amendment applied at 20 t/ha gave the highest yam tuber yield compared with other treatments and therefore recommended for yam production on an Alfisol for improving soil fertility conditions and sustained productivity

Nitrogen deposition effects on ecosystem services and interactions with other pollutants and climate change

Ecosystem services are defined as the ecological and socio-economic value of goods and services provided by natural and semi-natural ecosystems. Ecosystem services are being impacted by many human induced stresses, one of them being nitrogen (N) deposition and its interactions with other pollutants and climate change. It is concluded that N directly or indirectly affects a wide range of provisioning, regulating, supporting and cultural ecosystem services, many of which are interrelated. When considering the effects of N on ecosystem services, it is important to distinguish between different types of ecosystems/species and the protection against N impacts should include other aspects related to N, in addition to biodiversity. The Working Group considered the following priorities of ecosystem services in relation to N: biodiversity; air quality/atmosphere; ecosystem changes; NO3 leaching; climate regulation and cultural issues. These are the services for which the best evidence is available in the literature. There is a conflicting interest between greenhouse gas ecosystem services and biodiversity protection; up to some point of increasing N inputs, net greenhouse gas uptake is improved, while biodiversity is already adversely affected