Multi-Year Application of Dairy Slurry on Grassland: Effects on Crop, Soil Biota, Soil Nutrients, and N\u3csub\u3e2\u3c/sub\u3eO Emission

The long-term effects of using manure as the principal nutrient source in intensive crop production systems are not well known. This paper reports on the effects of multi-year application of fertilizer or dairy slurry on a tall fescue (Festuca arundinacea Schreb.) sward. Slurry sustained greater grass yield than chemical fertilizer. Unlike fertilizer, slurry supplied 70 to 120 kg N/ha one year after application but little after one year; 4-years of manure applications built up the stable organic matter pool in the soil. Manure-N was less prone to leaching but more prone to N2O emissions than fertilizer-N. Manured soils had considerably more biological activity than fertilized soils. High rates of manure application increased soil P

Distribution of cadmium in a cultivated soil in Britanny, France Distribuição de cádmio em solo cultivado na Bretanha, França

Cadmium (Cd) can be potentially toxic to the environment, and its bioavailability is related to the chemical forms it occurs in the soils. The distribution of Cd into the solid phase and its availability was investigated in a cultivated soil in Britanny, France. Cd sequential extraction was performed using a modified Tessier's sequential extraction protocol. Total content of Cd (n = 22 samples) ranged from 0.13 to 0.37 mg kg¹. Long term history of organic and mineral fertilizers application increased Cd concentration in the surface horizon. The fate of Cd was correlated with soil available P2O5 concentration and pH. The regression analysis (linear and non-linear) and Principal Component Analysis revealed the synergistic effect of P2O5 in the retention of Cd in cultivated soils. The following fractions' sequence was observed: bounded to Fe and Al oxides + phosphates > exchangeable > bound to organic matter » residual fraction.<br>O cádmio (Cd) pode ser tóxico no ambiente e sua biodisponibilidade está relacionada às formas químicas em que os metais se encontram no solo. Apresenta-se a distribuição deste metal na fase sólida de um solo cultivado na Bretanha, França, assim como fatores que influenciam sua disponibilidade. Foi realizada a extração sequencial do Cd utilizando o método Tessier, modificado. A concentração total de Cd, avaliada em 22 amostras, variou de 0,13 a 0,37 mg kg¹. O uso contínuo de fertilizantes orgânicos e minerais aumentou a concentração de Cd no horizonte superficial do solo. A distribuição do Cd foi relacionada à concentração de P2O5 disponível e ao pH. Análises de regressão (linear e não linear) e a Análise de Componentes Principais mostraram efeito sinérgico do P2O5 na retenção de Cd nos solos cultivados. O fracionamento apresentou a seguinte sequência: ligado a óxidos de Fe e de Al + fosfatos > trocável > ligado à matéria orgânica » residual