Residual effects of lime and sewage sludge inputs on soil fertility and tree and pasture production in a Pinus radiata D. Don silvopastoral system established in a very acidic soil

Abstract

In Galician (Spain) silvopastoral systems, nutrient availability to the pasture and trees can be limited by soil acidity. Liming and fertilisation with sewage sludge could enhance the productivity of silvopastoral systems (including understory and trees) by increasing Ca and reducing Al in the soil. This study evaluated changes in soil chemical properties, tree growth and understory production in test plots, both limed and unlimed, in a silvopastoral system located on an acidic forest soil under Pinus radiata D. Don. This research compared the effects of different doses of sewage sludge (160, 320 and 480 kg total N ha −1) with the effects of mineral fertilisation (8% N-24% P 2 O 5-16% K 2 O) and no fertilisation. The initial lime applications improved soil fertility (increasing soil pH, effective exchange capacity, and the saturation percentage of Ca and reducing the saturation percentage of Al) more than the sewage sludge. However, the most significant effects of sewage sludge were found over the long term after high doses of sewage sludge were applied (480 kg total N ha −1). Therefore, the use of sewage sludge as a fertiliser improves both soil fertility and the productivity of silvopastoral systems in the long term as long as an adequate disposal of this residue is guaranteed.

Phosphorous dynamics in poplar silvopastoral systems fertilised with sewage sludge

“…In 2005, the liming negatively affected the soil pH probably because the pasture production tended to improve when the soil was limed (Lime 400N) compared with the treatment without lime (No Lime 0N), increasing the extraction of cations from the soil and thus causing soil acidification. Similar results were previously observed in the same area in silvopastoral systems established with Pinus radiata D. Don in which some years after the last addition of lime to the soil the soil pH decreased, mainly due to the quickly growth of the plants favoured by liming and the climatic conditions (Mosquera-Losada et al, 2012;Ferreiro-Dominguez et al, 2014). The increase in pasture production associated with liming could be attributed to the increase in the exchangeable Ca, which tends to increase mineralisation of the soil organic matter, causing nutrient release (Wheeler, 1998) and, therefore, improving the physical and chemical soil properties (Slattery et al, 1995).…”

“…The total amount of sewage sludge produced in the EU is expected to be 13 million tons in 2020 (EU, 2008). Moreover, several studies have showed that the use of sewage sludge as fertiliser in the silvopastoral systems could enhance tree growth and pasture production (Mosquera-Losada et al, 2012;Ferreiro-Dominguez et al, 2011 while the botanical composition of the understory (Mosquera-Losada et al, 2009b) and the soil C storage are modified (Mosquera-Losada et al, 2015). However, using sewage sludge as fertiliser can represent a potential threat to the environment due to the possible addition to the soil of heavy metals and toxic organic compounds, the excess of labile organic matter and leachable N and P and the presence of pathogenic microorganisms (McBride, 2003;McLaren et al, 2004;De las Heras et al, 2005).…”

The effects of Alginite fertilization on selected tree species seedlings performance on afforested agricultural lands

“…Another paper, which compared the use of sewage sludge in comparison with the control and the area fertilized with mineral fertilizers (by 500 kg to 8% N -24% P 2 O 5 -16% K 2 O per hectare) also confirmed the positive effect of sewage sludge on the height of seedlings (Rigueira-Rodríguez et al 2010). On the other hand, the use of sewage sludge in combination with lime has not been confirmed as a positively functioning agent in the height of the seedlings (Mosquera-Losada et al 2012). Alginite influence with positive results in height increment has only been evaluated one year after planting Tužinský et al 2015).…”

Fertilização orgânica em sistemas silvipastoris

“…Como discutido na seção anterior, o uso de lodo de esgoto consiste em uma estratégia para elevar o pH do solo, o que se reflete também na sua relação com a planta. Mosquera-Losada et al (2012), trabalhando com um solo de pH em torno de 4,0, verificaram efeito da aplicação de calcário no desenvolvimento das árvores, apenas na ausência de lodo de esgoto. Portanto, com a aplicação desse insumo orgânico, pode-se suprimir a prática da calagem mesmo em solo ácido, sem prejuízo ao desenvolvimento das plantas.…”