Greater Soil Organic Matter Content Research Articles

The effect of organic and conventional management practices on soil macropore structure in greenhouse vegetable production

AbstractGreenhouse vegetable production (GVP) is developing rapidly and farming practices strongly affect soil quality. However, quantitative evidence of the differences in soil macropore structure between organic and conventional greenhouse vegetable cultivation is still unavailable. In this study, we sampled paired organic and conventional greenhouse vegetable soils from the tilled and plough pan layers at sample sites south of Nanjing, China. Using industrial computed tomography (CT) scanning technology to measure soil macropore characteristics, we examined the effects of different farming practices on soil macropore structure, as well as the main factors that influenced soil macropore characteristics. Organic greenhouse vegetable (OGV) production was associated with a greater quantity and quality of soil macropores compared with conventional greenhouse vegetable (CGV) production. The total macroporosity in the tilled soil layer averaged 16.9% in OGV soils, more than twice that of CGV soils. OGV soils exhibited an improved pore size distribution with a greater relative abundance of transmission pores (50–500 μm) and a decreased relative abundance of large macropores (>1,000 μm). Pore size and shape data suggested that OGV soils had fewer soil cracks but more biopores than CGV soils in the tilled layer, as well as more root biopores in the plough pan layer. Furthermore, macropore morphology was improved in both the tilled and plough pan layers of OGV soils. In particular, macropore connectivity was nearly 10 times greater in the tilled layer of OGV soils. Soil organic matter (SOM) content was the dominant factor influencing most macropore characteristics (total macroporosity, connectivity, and relative porosity of 100–1,000 μm pores, all small macropores and elongated medium macropores). We suggest that greater SOM content and consequently better soil macropore structure in OGV soils was dependent not only on greater organic manure input, but also on the non‐application of chemical fertilizer.Highlights Farm management affects soil macropore structure in greenhouse vegetable production. Compared soil macropore structure in organic and conventional greenhouse vegetable cultivation. OGV had greater quantity and quality of soil macropores than CGV. Greater SOM in organic farming contributed to the better soil macropore structure.

Effects of agricultural management practices on soil quality: A review of long-term experiments for Europe and China

In this paper we present effects of four paired agricultural management practices (organic matter (OM) addition versus no organic matter input, no-tillage (NT) versus conventional tillage, crop rotation versus monoculture, and organic agriculture versus conventional agriculture) on five key soil quality indicators, i.e., soil organic matter (SOM) content, pH, aggregate stability, earthworms (numbers) and crop yield. We have considered organic matter addition, no-tillage, crop rotation and organic agriculture as “promising practices”; no organic matter input, conventional tillage, monoculture and conventional farming were taken as the respective references or “standard practice” (baseline). Relative effects were analysed through indicator response ratio (RR) under each paired practice. For this we considered data of 30 long-term experiments collected from 13 case study sites in Europe and China as collated in the framework of the EU-China funded iSQAPER project. These were complemented with data from 42 long-term experiments across China and 402 observations of long-term trials published in the literature. Out of these, we only considered experiments covering at least five years. The results show that OM addition favourably affected all the indicators under consideration. The most favourable effect was reported on earthworm numbers, followed by yield, SOM content and soil aggregate stability. For pH, effects depended on soil type; OM input favourably affected the pH of acidic soils, whereas no clear trend was observed under NT. NT generally led to increased aggregate stability and greater SOM content in upper soil horizons. However, the magnitude of the relative effects varied, e.g. with soil texture. No-tillage practices enhanced earthworm populations, but not where herbicides or pesticides were applied to combat weeds and pests. Overall, in this review, yield slightly decreased under NT. Crop rotation had a positive effect on SOM content and yield; rotation with ley very positively influenced earthworms’ numbers. Overall, crop rotation had little impact on soil pH and aggregate stability − depending on the type of intercrop; alternatively, rotation of arable crops only resulted in adverse effects. A clear positive trend was observed for earthworm abundance under organic agriculture. Further, organic agriculture generally resulted in increased aggregate stability and greater SOM content. Overall, no clear trend was found for pH; a decrease in yield was observed under organic agriculture in this review.

Mixed-species plantation with Pinus massoniana and Castanopsis hystrix accelerates C loss in recalcitrant coniferous litter but slows C loss in labile broadleaf litter in southern China

Litter decomposition varies with forest type in complex ways and is significantly dependent on tree species diversity. A field litterbag experiment was conducted in monospecific and mixed-species plantations of Pinus massoniana and Castanopsis hystrix in subtropical China, to examine the effects of litter mixing and changing stand environment on the litter decomposition rate and the composition-specific litter organic C loss rate of P. massoniana and C. hystrix. Admixing with the lower-quality P. massoniana litter slowed C. hystrix litter decomposition and recalcitrant C loss, whereas admixing with the higher-quality C. hystrix litter hastened P. massoniana litter decomposition in the mixed-species plantation. The P. massoniana litter exhibited a faster decomposition rate in the mixed-species plantation than in the P. massoniana monospecific plantation. The same trend was found in the loss rates of aromatic C and carbonyl C from P. massoniana litter. The greater soil organic matter content and nitrogen availability in the mixed-species plantation than in the P. massoniana monospecific plantation could have resulted in the increased rates of decomposition and organic C loss in P. massoniana litter. This study highlights that maintaining mixed conifer-broadleaf forests and/or adopting close-to-nature forest management could accelerate the decomposition of recalcitrant coniferous litter, facilitating C sequestration and mitigating the C emissions derived from the labile broadleaf litter.

Movimentação vertical do íon potássio em Neossolos Quartzarênicos sob cultivo com cana-de-açúcar

Resumo O objetivo deste trabalho foi determinar a movimentação vertical do íon potássio em perfil de Neossolo Quartzarênico cultivado com cana-de-açúcar. Foram realizados dois experimentos, em campo. O primeiro consistiu de uma avaliação da movimentação do íon no perfil do solo até 1,80 m de profundidade, por dois anos, em uma área cultivada com cana-de-açúcar e em outra sob cerrado. O segundo consistiu da avaliação do movimento do íon até a profundidade de 1,00 m, sob dois regimes hídricos: natural e controlado. No experimento sob condições controladas, as avaliações foram feitas em parcelas de 0,5 m2, delimitadas por chapas galvanizadas, com adição de 80 kg ha-1 de K2O seguida da adição de 1.200 mm de água. A área sob lavoura apresentou maior conteúdo de matéria orgânica do solo, maior pH e, consequentemente, maior capacidade de retenção do K+ nas camada superficiais do perfil do que a área de cerrado. Além disso, na área sob lavoura, a avaliação da disponibilidade de K+ ao longo do perfil do Neossolo avaliado foi influenciada pelo tipo de regime hídrico adotado (chuva natural ou controlada). Independentemente do uso do solo, o K+ apresenta rápida movimentação no perfil do solo.

Soil and crop management and biomass removal effects on soil organic matter content in Hungary

Greater use of biomass for bioenergy has increased the need to evaluate above ground biomass removal (BR) effects on soil quality components, especially soil organic matter (SOM). A multifactor, 40 year fi eld experiment was conducted in Kompolt, Hungary on a carbonate-free, slightly acidic chernozem brown forest soil (USDA: Ustolls) with the objective of determining the effect of different management systems with concurrent removal of the above ground biomass on the SOM content of the 0-320 mm layer. A multifactor experiment composed of treatments involving different crop rotation (CR), beef manure application, mineral fertiliser application, above ground BR (vs. biomass incorporation, BI) and lucerne management options for different rotations are the basis of this study. CR had no signifi cant effect on SOM content. Management options that included a four year lucerne stand produced signifi cantly higher SOM content in fi ve out of six fertiliser and biomass management combinations. Continuous manure applications and manure + NPK fertiliser resulted in a signifi cantly greater SOM content than management options that minimised or eliminated fertiliser or manure additions. SOM content for different soil amendments and biomass treatments ranked: BR < NPK + BR < BI < manure + BR = NPK + manure + BR with SOM contents of 2.75 < 2.82 < 2.87 < 2.92 per cent (w/w) respectively. Manure had the most profound effect because its signifi cance was most consistent across a range of management combinations and years. The results suggest that agricultural management systems that include lucerne and manure application have the potential to sustain SOM content with concurrent above ground BR in continental climates on Ustolls with near level topography.

Soil and crop management and biomass removal effects on soil organic matter content in Hungary

Greater use of biomass for bioenergy has increased the need to evaluate above ground biomass removal (BR) effects on soil quality components, especially soil organic matter (SOM). A multifactor, 40 year fi eld experiment was conducted in Kompolt, Hungary on a carbonate-free, slightly acidic chernozem brown forest soil (USDA: Ustolls) with the objective of determining the effect of different management systems with concurrent removal of the above ground biomass on the SOM content of the 0-320 mm layer. A multifactor experiment composed of treatments involving different crop rotation (CR), beef manure application, mineral fertiliser application, above ground BR (vs. biomass incorporation, BI) and lucerne management options for different rotations are the basis of this study. CR had no signifi cant effect on SOM content. Management options that included a four year lucerne stand produced signifi cantly higher SOM content in fi ve out of six fertiliser and biomass management combinations. Continuous manure applications and manure + NPK fertiliser resulted in a signifi cantly greater SOM content than management options that minimised or eliminated fertiliser or manure additions. SOM content for different soil amendments and biomass treatments ranked: BR < NPK + BR < BI < manure + BR = NPK + manure + BR with SOM contents of 2.75 < 2.82 < 2.87 < 2.92 per cent (w/w) respectively. Manure had the most profound effect because its signifi cance was most consistent across a range of management combinations and years. The results suggest that agricultural management systems that include lucerne and manure application have the potential to sustain SOM content with concurrent above ground BR in continental climates on Ustolls with near level topography.

Investigating flow mechanisms in a forest soil by mixed‐effects modelling

Uniform and preferential flow produces typical infiltration patterns. We made three tracer experiments in a Norway spruce forest soil and qualitatively identified the dominant flow regime based on stained patterns. We analysed soil texture, fine root density and soil bulk density from preferential flow paths and the soil matrix by means of linear mixed‐effects models. These models can account for dependences in the data structure caused by hierarchical sampling and can deal with missing values. There were between 44% (topsoil) and 76% (subsoil) larger root densities in preferential flow paths than in the soil matrix. No significant differences in soil texture were detected. The bulk density was greater in the soil matrix by 0.12 g cm−3, which is probably because of a greater soil organic matter content of preferential flow paths. Using flow patterns and model results we identified the dominant flow mechanisms. At this study site, roots constituted the main preferential flow paths and induced macropore flow, especially in the topsoil. In the subsoil, root density decreased and inhomogeneous infiltration from preferential flow paths into the soil matrix caused unstable flow.

Sorção do herbicida imazaquin em Latossolo sob plantio direto e convencional

O objetivo deste trabalho foi avaliar o efeito da variabilidade do pH e da matéria orgânica de um Latossolo Vermelho distrófico, textura argilosa, sob diferentes manejos na retenção do herbicida imazaquin. A retenção deste herbicida foi medida pelo coeficiente de partição solo-água (Kd) em amostras de solos coletados na camada superficial (0-15 cm) em área de 38 ha, sob irrigação com pivô central e plantio direto e convencional. A retenção do imazaquin foi maior nas áreas com menores valores de pH e altos teores de matéria orgânica, ou seja, nas áreas onde o plantio direto foi utilizado por longo tempo. O pH afetou a retenção do imazaquin por controlar tanto a natureza iônica dos componentes do solo, matéria orgânica e minerais de argila, quanto a sua especiação. O teor de argila não apresentou variação na área estudada, ou seja, não afetou a retenção do imazaquin. O modelo de predição da sorção do imazaquin no solo pela análise de regressão multivariada com duas variáveis independentes (teor de matéria orgânica e pH) apresentou boa correlação (R² = 0,91).

SORPTION OF HERBICIDES IN RELATION TO SOIL VARIABILITY AND LANDSCAPE POSITION

Using the soil-water sorption partitioning coefficient (Kd), this study quantified the spatial variation of 2,4-D sorption by soil in an undulating-to-hummocky terrain landscape near Minnedosa, MB, Canada. Herbicide sorptionwas most strongly related to soil organic matter content and slope position, with greatest sorption occurring in lower landscape positions with greater soil organic matter content. The relation between sorption and slope position was more pronounced under conventional tillage (CT) than under long-term zerotillage (ZT). Using multivariate regression and three independent variables (soil organic matter content, soil clay content and soil pH), the prediction of herbicide sorption by soil was very good for CT (R2 = 0.89) and adequately for ZT (R2 = 0.53).

Influence of Microtopography and Canopy Species on Spatial Patterns of Forest Understory Plants

In a maple—beech forest in eastern New York, equal numbers of mounds, pits, and adjacent undisturbed soil microsites were caused for plant species density and cover over the growing seasons of 1978 and 1979. Several soil properties were also measured for each microsite. Detrended correspondence analysis (DCA) and chi—square goodness—of—fit tests were used to test whether the species were uniformly distributed over the microrelief positions. Comparisons of species composition, diversity, and vegetative phenologies were made between microsites and between hemlock— and hardwood—dominated forest areas. Differences in soil properties between microsites and between the two forest areas were assessed with one—tailed paried t test and Wilcoxon rank—sum tests, respectively. Microrelief created a mosaic of soil properties and a vegetation pattern in the understory, both of which were affected by the presence of hemlock in the canopy. Ordinations (DCA) indicated two factors that affected species compostion of the microsites: (1) presence of hemlock (Tsuga canadensis) as the nearest canopy tree, and (2) microtopography (whether the microsite was a mound, pit, or undisturbed—soil site). Species in non—hemlock areas had patchy distributions in the forest community: eight species grew mainly on mounds, six in pits, and five on undisturbed soil. The mounds and pits had characteristic assemblages of species. Species richness and total density and cover of plants in each microsite were constant over the growing season. In contrast, little spatial or temporal community pattern was apparent in forest areas influenced by hemlock. The effect of hemlock on species distributions was due in part to its effect on soil properties. For all microsites, forest areas with hemlock had greater soil organic matter content, available nitrogen, cation exchange capacity, and little depth, lower soil calcium content, moisture content, temperature, pH, and A1 horizon depth; and no frost heaving. Microrelief also affected soil properties significantly. In comparison with pits, mounds were drier and poorer in nutrient content, and had a lower cation exchange capacity, less organic matter, less little cover, a thinner A1 horizon, and less snow accumulation. In areas without hemlock, the mounds were also more acid, warmer in summer and colder in winter, and more subject to frost heaving than pits. Hemlock—influenced areas had no consistent microsite differences in pH or temperature. The different microenvirnments, created by the interaction of microrelief and hemlock, resulted in patchy distributions of most understory species. This pattern was likely a reuslt of species requirements for and tolerances of envirnomental conditions, tempered by competitive interactions.