Strategic Management of Grazing Grassland Systems to Maintain and Increase Organic Carbon in Soils

Understanding management-induced C sequestration potential in soils under agriculture, forestry, and other land use systems and their quantification to offset increasing greenhouse gases are of global concern. This chapter reviews management-induced changes in C storage in soils of grazing grassland systems, their impacts on ecosystem functions, and their adaptability and needs of protection across socio-economic and cultural settings. In general, improved management of grassland/pasture such as manuring/slurry application, liming and rotational grazing, and low to medium livestock units could sequester C more than under high intensity grazing conditions. Converting cultivated land to pasture, restoration of degraded land, and maximizing pasture phases in mixed-cropping, pasture with mixed-livestock, integrated forestry-pasturage of livestock (silvopastoral) and crop-forestry-pasturage of livestock (agro-silvopastoral) systems could also maintain and enhance soil organic C density (SOCρ). In areas receiving low precipitation and having high erodibility, grazing exclusion might restore degraded grasslands and increase SOCρ. Yet, optimizing C sequestration rates, sowing of more productive grass varieties, judicial inorganic and organic fertilization, rotational grazing, and other climate-resilient approaches could improve overall farm productivity and profitability and attain sustainability in livestock farming systems

Transpiration response of upland rice to water deficit changed by different levels of eucalyptus biochar

The objective of this work was to evaluate the effect of eucalyptus biochar on the transpiration rate of upland rice 'BRSMG Curinga' as an alternative means to decrease the effect of water stress on plant growth and development. Two-pot experiments were carried out using a completely randomized block design, in a split-plot arrangement, with six replicates. Main plots were water stress (WS) and no-water stress (NWS), and the subplots were biochar doses at 0, 6, 12 and 24% in growing medium (sand). Total transpirable soil water (TTSW), the p factor – defined as the average fraction of TTSW which can be depleted from the root zone before water stress limits growth –, and the normalized transpiration rate (NTR) were determined. Biochar addition increased TTSW and the p factor, and reduced NTR. Consequently, biochar addition was able to change the moisture threshold (p factor) of the growing medium, up to 12% maximum concentration, delaying the point where transpiration declines and affects yield.The objective of this work was to evaluate the effect of eucalyptus biochar on the transpiration rate of upland rice 'BRSMG Curinga' as an alternative means to decrease the effect of water stress on plant growth and development. Two‑pot experiments were carried out using a completely randomized block design, in a split-plot arrangement, with six replicates. Main plots were water stress (WS) and no‑water stress (NWS), and the subplots were biochar doses at 0, 6, 12 and 24% in growing medium (sand). Total transpirable soil water (TTSW), the p factor – defined as the average fraction of TTSW which can be depleted from the root zone before water stress limits growth –, and the normalized transpiration rate (NTR) were determined. Biochar addition increased TTSW and the p factor, and reduced NTR. Consequently, biochar addition was able to change the moisture threshold (p factor) of the growing medium, up to 12% maximum concentration, delaying the point where transpiration declines and affects yield

Estoques de carbono e nitrogênio de um Neossolo Quartzarênico sob cultivo de fruteiras irrigadas na região do semi-árido do Brasil

Soil organic matter accumulation provides benefits to soil productivity and reduces atmospheric carbon concentration. However, little is known about the accumulation of C and N by sandy soils under perennial irrigated crops in semiarid regions. The objective of this study was to evaluate the effect of irrigated fruit orchard cultivation on the stocks of soil organic carbon (SOC) and total nitrogen (N) of an Arenosol/Quartzpsament from Paraipaba-CE, Semiarid Brazil. Soil samples were taken from irrigated orchards of banana (Musa ssp.), cashew (Anacardium ocidentale), guava (Psidium guajava), bullock's heart (Annona reticulata), mango (Mangifera indica), and sapote (Manilkara zapota) in the wetted-bulb and non-irrigated area between the plant rows. Additional samples were collected from adjacent areas under secondary Caatinga forest, and under a 2-year-old deforested area. Sampling depths were: 0-0.1, 0.1-0.2, and 0.2-0.4 m. The highest contents of SOC and N were found in the surface layer. The soil bulk density did not change in depth. The stocks of SOC and total N under secondary forest at 0-0.40 m layer were 27.6 and 2.4 Mg ha-1, respectively. Caatinga Forest conversion into fruit orchard cultivation led to a decrease of 5 to 23% and 4 to 21% on SOC and N stocks, respectively. Compared to other soil uses, sapote and bullock's heart contributed for a lower decrease of SOC and N stocks after deforestation. Guava, bullock's heart, mango and sapote contributed for improving the SOC stratification index.O acúmulo de matéria orgânica beneficia a produtividade do solo e reduz a concentração do carbono atmosférico. Entretanto, pouco é sabido a respeito do acúmulo de C e N em solos arenosos cultivados com culturas perenes irrigadas em regiões semi-áridas. O objetivo deste trabalho foi avaliar o efeito do cultivo de fruteiras irrigadas nos estoques de C e N de um Neossolo Quartzarênico em Paraipaba, CE. Foram coletadas amostras na linha e na entrelinha de pomares irrigados de banana, caju, manga, sapoti, goiaba e graviola. Em áreas adjacentes sob vegetação de Caatinga hipoxerófila e após dois anos de desmatamento foram coletadas amostras adicionais. As profundidades de amostragem foram: 0 a 0.1, 0.1 a 0.2 e 0.2 a 0.4 m. Os teores de C e N no solo foram mais altos na camada superficial (0 a 0.1 m). Não houve efeito da profundidade de amostragem sobre a densidade do solo. Os estoques de C e N na área com vegetação de Caatinga na camada de 0 a 0.4 m foram de 27,6 and 2,4 Mg ha-1, respectivamente. A retirada da vegetação natural e o cultivo das fruteiras levaram a reduções de 5 a 23% e 4 a 21% nos estoques de C e N do solo, respectivamente. As culturas do sapoti e da graviola contribuíram para o aumento dos estoques de C e N após a retirada da vegetação natural. As culturas da goiaba, graviola, manga e sapoti contribuíram para a melhoria do índice de estratificação deste solo

Efeito da temperatura de carbonização sobre características físico- químicas dos carvões de duas espécies de bambu: Effect of pyrolisis temperature on physicochemical properties of biochars made from two different bamboo species

Por sua alta eficiência fotossintética e conversão em biomassa, o bambu tem gran- de potencial para a produção de carvão de uso agrícola (biocarvão). Este trabalho comparou os carvões produzidos a diferentes temperaturas de pirólise a partir do colmo de duas espécies de larga ocorrência no sul do país: Phyllostachys aurea (uma espécie exótica) e Guadua sp. (na- tiva do sul do Brasil). Os resultados mostraram diferenças entre as duas espécies, a começar pelo teor de lignina e de voláteis dos colmos in natura, sendo que a espécie exótica mostrou maiores teores de lignina e menores de extrati- vos. Estas diferenças se refletem no processo de pirólise e nas características químicas dos carvões, sendo que a espécie exótica produz carvões com maiores teores de carbono

Balanço energético e pegada de carbono nos sistemas de produção integrada e convencional de feijão-comum irrigado

The objective of this work was to evaluate the contribution of an integrated farming system (PI) of common bean, in comparison with convectional farming, as to energy use, energy efficiency, and carbon footprint, considered from input manufacturing to grain harvest in the farms, excluding transport. Four farmswere selected in Cristalina, state of Goiás, Brazil, during the third harvest season of common bean, in 2009. The PI system reduced the average energy use by 3.1%, in comparison with the conventional system. Values ranged from 22,759.9 to 25,518.4 Mg ha-1. Mineral N fertilization with 6,584.0 MJ ha-1, agricultural operations with 5,309.4 MJ ha-1, and irrigation with 4,961.4 MJ ha-1 had the largest participation in energy use. Energy efficiency in PI (2.16) was higher than in the conventional system (2.01). There was no significant difference between the two systems as to carbon footprint per hectare, but carbon footprint per kilogram of yielded bean in PI (0.301 kg CO2-eq kg-1) was significantly lower than in conventional system (0.325 kg CO2-eq kg-1). The improvement of N fertilizer use efficiency by N biological fixation and the rationalization of machinery are the production system components that contributes the most for the reduction of carbon footprint.O objetivo deste trabalho foi avaliar a contribuição do sistema de produção integrada de feijão‑comum (PI), em comparação ao sistema de produção convencional, quanto ao uso de energia, à eficiência energética e à pegada de carbono, contabilizados desde a fabricação de insumos até a colheita de grãos nas fazendas, tendo-se excluído o transporte. Foram selecionadas quatro fazendas em Cristalina, GO, na terceira época de produção de feijão, em 2009. O sistema PI reduziu o uso médio de energia em 3,1%, em comparação ao convencional. Os resultados variaram de 22.759,9 a 25.518,4 MJ ha-1. A adubação nitrogenada com 6.584,0 MJ ha-1, as operações mecanizadas com 5.309,4 MJ ha-1 e a irrigação com 4.961,4 MJ ha-1 tiveram a maior participação quanto ao uso de energia. A eficiência energética em PI (2,16) foi superior à observada no sistema convencional (2,01). Não houve diferença significativa entre os dois sistemas quanto à pegada de carbono por hectare, mas a pegada de carbono por quilograma de feijão produzido no PI (0,301 kg CO2-eq kg-1) foi significativamente menor do que no convencional (0,325 kg CO2-eq kg-1). A melhora da eficiência da adubação nitrogenada, por meio do uso de fixação biológica de N, e a racionalização da mecanização são os componentes dos sistemas de produção que mais contribuem para a diminuição da pegada de carbono

Disponibilidade de nitrogênio, espaço poroso preenchido por água e fluxos de N 2 O-N após aplicação de biochar e fertilização nitrogenada

The objective of this work was to investigate the impact of the application of wood biochar, combined with N fertilizations, on N2O-N fluxes, nitrogen availability, and water-filled pore space (WFPS) of a clayey Oxisol under rice (wet season) and common bean (dry season) succession. Manual static chambers were usedto quantify N2O-N fluxes from soil immediately after a single application of wood biochar (32 Mg ha-1) andafter four crop seasons with N applications (90 kg ha-1 N). Soil ammonium (N-NH4 +) and nitrate (N-NO3-) availability, as well as WFPS, was measured together with N2O-N fluxes. There was no interaction between biochar and N fertilization regarding N2O-N fluxes in any of the four seasons monitored, although these fluxes were clearly enhanced by N applications. At 1.5 and 2.5 years after biochar application, the WFPS decreased. In addition, in the seasons characterized by low WFPS, N2O-N fluxes and soil N-NO3- and N-NH4+ availability were enhanced after N applications. Long-term experiments in the field are important to quantify the impacts of biochar on N2O-N fluxes and to determine the dynamics of these fluxes on soil-related variables.O objetivo deste trabalho foi investigar o impacto da aplicação de biochar de madeira, combinada com fertilizações itrogenadas, nos fluxos de N2O-N, na disponibilidade de nitrogênio e no espaço poroso preenchido por água (EPPA), em um Latossolo argiloso sob sucessão com arroz (época chuvosa) e feijão (época seca). Câmaras estáticas manuais foram utilizadas para quantificar os fluxos de N2O-N no solo logo após uma única aplicação de biochar (32 Mg ha-1) e após quatro épocas de cultivo com aplicações de N (90 kg ha-1 de N). A disponibilidade de amônio (N-NH4+) e de nitrato (N-NO3-) no solo, bem como o EPPA, foi medida juntamente com os fluxos de N2O-N. Não houve interação entre biochar e fertilização nitrogenada quanto aos fluxos de N2O-N, em nenhuma das quatro épocas monitoradas, apesar de esses fluxos terem aumentado com as aplicações de N. Aos 1,5 e 2,5 anos após a aplicação do biochar, o EPPA diminuiu. Além disso, nas épocas caracterizadas por reduzido EPPA, os fluxos de N2O-N e a disponibilidade de N-NO3- e N-NH4 + no solo aumentaram após as aplicações de N.Experimentos em campo de longa duração são importantes para quantificar o impacto do uso de biochar sobre os fluxos de N2O-N e para determinar a dinâmica desses fluxos sobre as variáveis relacionadas ao solo

Revista Brasileira de Ciência do Solo

p. 85-93Fertility properties, total C (Ctot), and chemical soil organic matter fractions (fulvic acid fraction - FA, humic acid fraction - HA, humin fraction - H) of anthropogenic dark earths (Terra Preta de Índio) of the Amazon basin were compared with those of Ferralsols with no anthropogenic A horizon. Terra Preta soils had a higher fertility (pH: 5.1-5.4; Sum of bases, SB: 8.93-10.33 cmolc kg-1 , CEC: 17.2-17.5 cmolc kg-1 , V: 51-59 %, P: 116-291 mg kg-1) and Ctot (44.6-44.7 g kg-1) than adjacent Ferralsols (pH: 4.4; SB: 2.04 cmolc kg-1, CEC: 9.5 cmolc kg-1, V: 21 %, P 5 mg kg-1, C: 37.9 g kg-1). The C distribution among humic substance fractions (FA, HA, H) in Terra Preta soils was also different, as shown by the ratios HA:FA and EA/H (EA=HA+FA) (2.1-3.0 and 1.06-1.08 for Terra Preta and 1.2 and 0.72 for Ferralsols, respectively). While the cation exchange capacity (CEC), of Ferralsols correlated with FA (r = 0.97), the CEC of Terra Preta correlated with H (r = 0.82). The correlation of the fertility of Terra Preta with the highly stable soil organic matter fraction (H) is highly significant for the development of sustainable soil fertility management models in tropical ecosystems