C‐CO2 Emissions, Carbon Pools and Crop Productivity Increased upon Slaughterhouse Organic Residue Fertilization in a No‐Till System

The use of slaughterhouse organic residues (SORs) as a form of fertilization in no‐till systems could be an alternative to promote their appropriate disposal. This chapter reports a study on a Haplic Cambisol (Inceptisol) regarding the influence of different rates of SORs applied isolated or together with synthetic mineral fertilizers (SMFs) for 5.5 years in a no‐till system with diverse crop rotation. We evaluated crop productivity and several soil organic matter pools affected by the SOR and SMF combinations in a field experiment. In addition, a laboratory incubation experiment was performed with different rates of SORs to evaluate C‐CO2 emissions and C dynamics. The SOR applications provided significant increases in crop productivity, soil organic matter pools and C‐CO2 emissions. The SOR applications provided significant increases in crop productivity, soil organic matter pools and C-CO2 emissions. The treatment with 50% SOR + 50% SMF was the best alternative to provide higher crop productivity, while the higher use of SOR promoted more increments in soil organic matter levels. Despite the increase in C‐CO2 emissions due to the use of SORs, higher C levels were observed as a function of SOR rates. We conclude that the application of SORs combined with SMFs represents an efficient strategy to reduce costs and increase C levels, providing agronomic and environmental benefits

Molecular diversity and the fate of biochemical fractions of eucalypt tissues in soil

The molecular diversity of the source substrate has been regarded as a significant controller of the proportion of plant material that is either mineralized or incorporated into soil organic matter (SOM). However, quantitative parameters to express substrate molecular diversity remain elusive. In this research, we fractionated leaves, twigs, bark, and root tissues of 13C-enriched eucalypt seedlings into hot water extractables (HWE), total solvent (acetone) extractables (TSE), a cellulosic fraction (CF), and the acid unhydrolyzable residue (AUR). We used 13C NMR spectroscopy to obtain a molecular diversity index (MDI) based on the relative abundance of carbohydrate, protein, lignin, lipid, and carbonyl functional groups within the biochemical fractions. Subsequently, we obtained artificial plant organs containing fixed proportions (25%) of their respective biochemical fractions to be incubated with soil material obtained from a Haplic Ferralsol for 200-days, under controlled temperature (25 ± 1 ◦C) and moisture adjusted to 70–80% of the soil water holding capacity. Our experimental design was a randomized complete block design, arranged according to a factorial scheme including 4 plant organs, 4 biochemical fractions, and 3 blocks as replicates. During the incubation, we assessed the evolution of CO2 from the microcosms after 1, 2, 3, 4, 7, 10, 13, 21, 28, 38, 45, 70, 80, 92, 112, 148, 178 and 200 days from the start of the incubation. After the incubation, soil subsamples were submitted to a density fractionation to separate the light fraction of SOM (LFOM) i.e., with density <1.8 g cm 3. The heavy fraction remaining was submitted to wetsieving yielding the sand-sized SOM (SSOM) and the mineral-associated SOM (MAOM), with particle-size greater and smaller than 53 μm, respectively. We found that HWE and AUR exhibited comparatively higher MDIs than the TSE and CF. During the incubation, HWE and CF were the primary sources of 13C-CO2 from all plant organs and after 92 days, the respiration of the TSE of bark and roots increased. Otherwise, the AUR contributed the least for the release of 13C-CO2. There were no significant relationships between the MDI and the amount of 13C transferred into the LFOM or SSOM. Otherwise, the transfer of 13C into the MAOM increased as a linear-quadratic function of MDI, which in turn was negatively correlated with the total 13C-CO2 loss. Overall, the MDI exerted a stronger control on the 13C-labeled MAOM than on 13C-CO2 emissions, highlighting the need to improve our ability to distinguish and quantify direct plant inputs from those of microbial origin entering soil C pools.publishedVersio

Microscale spatial distribution and soil organic matter persistence in top and subsoil

The spatial distribution of organic substrates and microscale soil heterogeneity significantly influence organic matter (OM) persistence as constraints on OM accessibility to microorganisms. However, it is unclear how changes in OM spatial heterogeneity driven by factors such as soil depth affect the relative importance of substrate spatial distribution on OM persistence. This work evaluated the decomposition and persistence of 13C and 15N labeled water-extractable OM inputs over 50 days as either hotspot (i.e., pelleted in 1 – 2 mm-size pieces) or distributed (i.e., added as OM < 0.07 µm suspended in water) forms in topsoil (0-0.2 m) and subsoil (0.8-0.9 m) samples of an Andisol. We observed greater persistence of added C in the subsoil with distributed OM inputs relative to hotspot OM, indicated by a 17% reduction in cumulative mineralization of the added C and a 10% higher conversion to mineral-associated OM. A lower substrate availability potentially reduced mineralization due to OM dispersion throughout the soil. NanoSIMS (nanoscale secondary ion mass spectrometry) analysis identified organo-mineral associations on cross-sectioned aggregate interiors in the subsoil. On the other hand, in the topsoil, we did not observe significant differences in the persistence of OM, suggesting that the large amounts of particulate OM already present in the soil outweighed the influence of added OM spatial distribution. Here, we demonstrated under laboratory conditions that the spatial distribution of fresh OM input alone significantly affected the decomposition and persistence of OM inputs in the subsoil. On the other hand, spatial distribution seems to play a lower role in topsoils rich in particulate OM. The divergence in the influence of OM spatial distribution between the top and subsoil is likely driven by differences in soil mineralogy and OM composition.Microscale spatial distribution and soil organic matter persistence in top and subsoilpublishedVersio

Soil carbon and fertility attributes in response to surface liming under no‑tillage

O objetivo deste trabalho foi avaliar o efeito da aplicação de calagem superficial sobre o conteúdo de carbono orgânico total (COT) do solo, em plantio direto, e identificar a relação entre esse conteúdo e outros atributos de fertilidade. O experimento foi realizado em Latossolo Vermelho de textura média, em Ponta Grossa, PR. Os tratamentos consistiram da aplicação de calcário dolomítico na superfície do solo, nas doses 0 e 6 Mg ha‑1, em 1993, e da reaplicação de 0 e 3 Mg ha‑1, em 2000, nas parcelas com e sem calcário. O solo foi coletado em 2008, e foram analisados os conteúdos de COT e os atributos de fertilidade. A calagem produziu aumento do conteúdo de COT e da saturação por bases, e diminuição da saturação por alumínio. O conteúdo de COT apresentou relação linear com a capacidade de troca catiônica (CTC) efetiva e correlação com os teores de P e K. A CTC potencial apresentou correlação com o COT, e a CTC efetiva com o pH. A calagem superficial em sistema plantio direto, em longo período, proporciona aumento no conteúdo de COT e de N total.The objective of this work was to evaluate the effect of surface liming on the content of total organic carbon (TOC) of a soil under no‑tillage, and to identify the relationship between that content and other fertility attributes. The experiment was carried out on a medium‑textured Oxisol in Ponta Grossa, PR, Brazil. The treatments consisted of the application of 0 and 6 Mg ha‑1 of dolomitic lime on soil surface in 1993 and of the reapplication of 0 and 3 Mg ha‑1 in 2000, on plots with or without lime. The soil was collected in 2008, and the TOC content and fertility attributes were evaluated. Liming increased TOC content and base saturation, and decreased aluminium saturation. TOC content showed a linear relation with the effective cation exchange capacity and correlation with the levels of P and K. The potential CEC showed correlation with TOC, and the effective CEC with pH. Liming under no‑tillage, for a long period of time, increases TOC and total N contents

Stabilisierung organischer Substanzen durch mineralische Wechselwirkungen mit Fe und Al (hydro) oxiden im Boden

This thesis aimed to investigate mechanisms for soil organic matter (SOM) protection, focused on organo-mineral associations. The thesis innovates by discerning the relative roles of Fe and Al oxides in promoting soil organo-mineral associations in contrasting climate conditions. It provides important recommendations for avoiding clay re-aggregations at the microscale during SOM fractionation. It also demonstrates the yet under-recognized influence of microscale spatial distribution on SOM mineralization and stabilization in soils.Ziel dieser Arbeit war es, Mechanismen für die Stabilisierung organischer Bodensubstanz (OBS) zu untersuchen, vor allem diejenigen organo-mineralischer Assoziationen. Zu den neuen Erkenntnissen dieser Arbeit gehört die Unterscheidung der jeweiligen Rolle von Fe- und Al-Oxiden organo-mineralische Assoziationen im Boden unter kontrastierenden Klimabedingungen zu begünstigen. Die Arbeit liefert wichtige Empfehlungen zur Vermeidung der Re-Aggregierung von Tonpartikeln auf der Mikroskala während der Fraktionierung von OBS. Außerdem zeigt diese Arbeit auch den bislang noch wenig bekannten Einfluss den die mikroräumliche Verteilung auf die Mineralisierung und Stabilisierung von OBS in Böden hat

Stabilisierung organischer Substanzen durch mineralische Wechselwirkungen mit Fe und Al (hydro) oxiden im Boden

This thesis aimed to investigate mechanisms for soil organic matter (SOM) protection, focused on organo-mineral associations. The thesis innovates by discerning the relative roles of Fe and Al oxides in promoting soil organo-mineral associations in contrasting climate conditions. It provides important recommendations for avoiding clay re-aggregations at the microscale during SOM fractionation. It also demonstrates the yet under-recognized influence of microscale spatial distribution on SOM mineralization and stabilization in soils.Ziel dieser Arbeit war es, Mechanismen für die Stabilisierung organischer Bodensubstanz (OBS) zu untersuchen, vor allem diejenigen organo-mineralischer Assoziationen. Zu den neuen Erkenntnissen dieser Arbeit gehört die Unterscheidung der jeweiligen Rolle von Fe- und Al-Oxiden organo-mineralische Assoziationen im Boden unter kontrastierenden Klimabedingungen zu begünstigen. Die Arbeit liefert wichtige Empfehlungen zur Vermeidung der Re-Aggregierung von Tonpartikeln auf der Mikroskala während der Fraktionierung von OBS. Außerdem zeigt diese Arbeit auch den bislang noch wenig bekannten Einfluss den die mikroräumliche Verteilung auf die Mineralisierung und Stabilisierung von OBS in Böden hat

Stabilisierung organischer Substanzen durch mineralische Wechselwirkungen mit Fe und Al (hydro) oxiden im Boden

This thesis aimed to investigate mechanisms for soil organic matter (SOM) protection, focused on organo-mineral associations. The thesis innovates by discerning the relative roles of Fe and Al oxides in promoting soil organo-mineral associations in contrasting climate conditions. It provides important recommendations for avoiding clay re-aggregations at the microscale during SOM fractionation. It also demonstrates the yet under-recognized influence of microscale spatial distribution on SOM mineralization and stabilization in soils.Ziel dieser Arbeit war es, Mechanismen für die Stabilisierung organischer Bodensubstanz (OBS) zu untersuchen, vor allem diejenigen organo-mineralischer Assoziationen. Zu den neuen Erkenntnissen dieser Arbeit gehört die Unterscheidung der jeweiligen Rolle von Fe- und Al-Oxiden organo-mineralische Assoziationen im Boden unter kontrastierenden Klimabedingungen zu begünstigen. Die Arbeit liefert wichtige Empfehlungen zur Vermeidung der Re-Aggregierung von Tonpartikeln auf der Mikroskala während der Fraktionierung von OBS. Außerdem zeigt diese Arbeit auch den bislang noch wenig bekannten Einfluss den die mikroräumliche Verteilung auf die Mineralisierung und Stabilisierung von OBS in Böden hat

Carbono do solo e atributos de fertilidade em resposta à calagem superficial em plantio direto

O objetivo deste trabalho foi avaliar o efeito da aplicação de calagem superficial sobre o conteúdo de carbono orgânico total (COT) do solo, em plantio direto, e identificar a relação entre esse conteúdo e outros atributos de fertilidade. O experimento foi realizado em Latossolo Vermelho de textura média, em Ponta Grossa, PR. Os tratamentos consistiram da aplicação de calcário dolomítico na superfície do solo, nas doses 0 e 6 Mg ha-1, em 1993, e da reaplicação de 0 e 3 Mg ha-1, em 2000, nas parcelas com e sem calcário. O solo foi coletado em 2008, e foram analisados os conteúdos de COT e os atributos de fertilidade. A calagem produziu aumento do conteúdo de COT e da saturação por bases, e diminuição da saturação por alumínio. O conteúdo de COT apresentou relação linear com a capacidade de troca catiônica (CTC) efetiva e correlação com os teores de P e K. A CTC potencial apresentou correlação com o COT, e a CTC efetiva com o pH. A calagem superficial em sistema plantio direto, em longo período, proporciona aumento no conteúdo de COT e de N total