Short-term carbon dioxide emission under contrasting soil disturbance levels and organic amendments

Abstract

A B S T R A C TAgriculture can be either a source or sink of atmospheric CO 2 depending on soil management. The application of swine slurry in conventional tilled soils could enhance soil CO 2 emission depleting soil organic C stocks. However, the use of recalcitrant C-rich organic fertilizers in no-till soils can offset soil CO 2 emission promoting soil C sequestration. This hypothesis was tested by evaluating short-term CO 2 -C emissions from a Rhodic Nitisol under contrasting soil disturbance levels (disturbed (DS) and undisturbed soil (US)) top-dressed with mineral or organic fertilizers (urea (UR), raw swine slurry (RS), anaerobically digested swine slurry (ADS), and composted swine slurry (CS)). Soil CO 2 emission was evaluated for 64 days using static chambers where gas samples were collected and analysed by photoacoustic infrared spectroscopy. Soil water-filled pore space (WFPS), temperature and meteorological data were concomitantly registered and a first-order exponential decay model was used to assess the decomposition of organic fertilizers and CO 2 emissions induced by soil disturbance. Soil CO 2 -C emission was correlated with soil temperature, while limiting soil aeration impaired CO 2 -C efflux when WFPS >0.6 cm 3 cm À3 . Disturbance increased soil CO 2 -C efflux (36.3 AE 2.2 kg CO 2 -C ha À1 day À1 ) in relation to US (33.3 AE 1.6 kg CO 2 -C ha À1 day À1 ). Extra labile C input through RS amendment induced an increased soil CO 2 -C efflux for a longer period (t 1/2 = 16.9 and 9.6 days in DS and US treatments, respectively), resulting in higher CO 2 -C emissions than soil amended with other fertilizers. The recalcitrant C input by ADS and CS had limited effect on soil CO 2 -C emissions. CS presented a genuine potential for substantial soil organic C accumulation while offsetting increased CO 2 -C emissions in comparison to RS amended soils.

Poultry Litter and Pig slurry Applications in an Integrated Crop-Livestock System

“…Specific recommendations include the development of critical P limits (Gatiboni et al, 2015) to obtain the expected benefits from the chemical, physical, and biological properties of the soil and subsequent crop yield (Mafra et al, 2014;Grave et al, 2015). The concept has been adopted that organic fertilizers help promote system sustainability and should not be regarded as a potential source of environmental pollutants (Lourenzi et al, 2013).…”

Emissão de CO2 do solo pela aplicação de fertilizantes orgânicos e minerais em ambiente controlado

“…Contraditoriamente aos resultados citados anteriormente, Grave et al (2015) encontraram maiores emissões de CO 2 quando resíduos orgânicos foram incorporados ao solo. No entanto, esses resultados foram apenas 9% superiores aos tratamentos com disposição dos resíduos orgânicos na superfície do solo.…”

“…Este fator pode ser desejado quando se procura mineralização mais rápida dos nutrientes da palhada, para aproveitamento pelo cultivo subsequente. Grave et al (2015)…”

Fundamentos da digestão anaeróbia, purificação do biogás, uso e tratamento do digestato

“…c) Para atender a demanda de K 2 O: A = 120/0,8 x 1,0 = 150 m 3 .ha -1 . Ressalta-se que a opção pela dose mais alta (500 m 3 .ha -1 ) visando atender a demanda de P 2 O 5 resultaria em um aporte excessivo de 480 kg N ha -1 e 280 kg K 2 O ha -1 , o que deve ser evitado a fim de se mitigar possíveis impactos ambientais, especialmente relacionados à lixiviação de nitrato e potássio, volatilização de amônia e emissão de óxido nitroso (Aita et al, 2014). Neste caso, a opção tecnicamente correta seria optar pela menor dose (125 m 3. ha -1 ), visando atender a demanda de N do milho, e complementar a adubação com P e K através de outra fonte de fertilizante mineral (Nicoloso et al, 2016a).…”

“…A aplicação excessiva de fertilizantes, independente da origem mineral ou orgânica, pode causar impactos ambientais significativos, especialmente devido ao aumento das perdas de nutrientes do solo e sua transferência para o ambiente (Aita et al, 2014;Escosteguy et al, 2016;Soares et al, 2014). Neste sentido, inúmeras iniciativas de pesquisa vêm procurando estabelecer indicadores e limites críticos ambientais (LCAs) de disponibilidade de nutrientes no solo a fim de minorar os riscos de poluição ambiental.…”