Nitrogen and phosphorus availability to ryegrass in an acidic and limed zeolite-amended soil

Nitrogen and P fertilization increases crop yields, especially in acidic soils, but its effect may be minimized by various N loss and P retention processes. Zeolite may enhance N and P fertilizer efficiency. The aim of this study was to compare N and P availability and recovery efficiencies to ryegrass, as well as soil available nitrogen, in acidic and limed zeolite-added soils. In a pot experiment with ryegrass we added escalating zeolite quantities to an acidic and limed soil and we measured soil NH4-N dynamics and N and P in plant. Added zeolite protected NH4-N by releasing it more slowly when compared to the no-zeolite treatments. Recovery efficiency (uptake compared to added nutrient) increased with zeolite from 11.7% (no-zeolite) to 30% (zeolite treatment) for N and from 1.52% to 4.02% for P. Even under the unfavourable conditions of an acidic soil, N and P recovery efficiencies were greatly improved due to zeolite. This was induced by the slow release of ammonium cations, which kept the available NH4-N unchanged and due to the protection of the available P from being retained onto soil colloids

Phosphorus Availability in Low-P and Acidic Soils as Affected by Liming and P Addition

Acidic soils typically suffer from high phosphorus (P) retention, a problem that can be dealt with using greater P fertilization, soil liming, or both. The aim of this work was to examine which of these practices bears the more beneficial result for Lolium perenne L. growth. In a pot experiment, five acidic soils were treated as follows: L0P0 (unamended control), L1P0 (liming only), L0P1 (P addition only), and L1P1 (both liming and P addition). We found that P amendment alone was sufficient to increase plant P levels when the initial soil P concentrations were low. Liming without P addition increased plant P satisfactorily only in the high-P soil. We conclude that P addition alone is a better practice than liming alone for improved plant growth conditions in acidic, low-P soils, unless there is relatively high P content in soil, in which case liming alone may be sufficient to increase P availability

Relationships among nutritive value of selected forages, diet composition and milk quality in goats grazing in a Mediterranean woody rangeland

Woody rangelands are important forage resources for grazing goats in the Mediterranean basin. Goats are well adapted in these heterogeneous and complex ecosystems due to their particular anatomic characteristics, metabolic efficiency and browsing ability. However, the mechanism of grazing behavior and forage selection in goats is quite complex and depends on several factors. The present study deals with the seasonal changes of chemical composition in the selected forages and ingested diets as well as their effects on milk yield and composition of goats grazing in a Mediterranean woody rangeland. Hand plucked forage samples similar to those consumed by the goats were collected for chemical analysis. The nutritive value of consumed forages, in combination with the different feeding and grazing system per trial period, influenced milk quality and performance. The replacement of feed supplementation with an increase of the contribution of grazing in the rangeland could maintain the milk yield and quality at the late stage of lactation. In addition, this paper focuses on the influence of the chemical composition of selected forages on the diet selection of goats using a modeling approach. The model showed a high interpretative accuracy and explanatory value (R2 = 0.923) and was able to distinguish the goats' most important criteria for selecting among the forage plant species in relation to several factors. The results indicate that the dietary preferences of goats were influenced, not only by the seasonality of nutritive value and availability of forages in the rangeland, but also by the plant origin of each nutrient source. The selection of Quercus frainetto was highly correlated with its NDF content. Herbaceous species, Cistus creticus and other woody species were mainly selected due to their CP content. The ADL content seemed to have the lowest influence of all nutritive variables on the selection among groups of plant species. The modeling approach, apart from the understanding of grazing behavior of goats, offers additional information that can be useful to the shepherds in order to manage more effectively the feeding and grazing system of their goat's flock