Ecosystem services in smallholder coffee farming systems: a case study in Uganda using chemical soil indicators

Farmers in coffee producing countries may not be aware of the economic, social and ecological benefits available through organic agriculture. At a local, regional and global scale, smallholder coffee farmers can discover that organic production methods are linked to provisioning, regulating, cultural and supporting ecosystem services. It is assumed that organic agriculture has a significant influence on soil parameters, and by association, on ecosystem services. Differences between farming systems in soil chemical properties reveal advantages for coffee farmers and shows the ecosystem services derived through organic agriculture at a local level. Benefits discovered in organic coffee systems are higher inputs of organic matter, higher biodiversity of soil microorganisms, less soil erosion, and the potential for higher aggregate stability and superior nutrient circulation

Gross Ammonification and Nitrification Rates in Soil Amended with Natural and NH4-Enriched Chabazite Zeolite and Nitrification Inhibitor DMPP

Using zeolite-rich tuffs for improving soil properties and crop N-use efficiency is becoming popular. However, the mechanistic understanding of their influence on soil N-processes is still poor. This paper aims to shed new light on how natural and NH4+-enriched chabazite zeolites alter short-term N-ammonification and nitrification rates with and without the use of nitrification inhibitor (DMPP). We employed the 15N pool dilution technique to determine short-term gross rates of ammonification and nitrification in a silty-clay soil amended with two typologies of chabazite-rich tuff: (1) at natural state and (2) enriched with NH4+-N from an animal slurry. Archaeal and bacterial amoA, nirS and nosZ genes, N2O-N and CO2-C emissions were also evaluated. The results showed modest short-term effects of chabazite at natural state only on nitrate production rates, which was slightly delayed compared to the unamended soil. On the other hand, the addition of NH4+-enriched chabazite stimulated NH4+-N production, N2O-N emissions, but reduced NO3-N production and abundance of nirS-nosZ genes. DMPP efficiency in reducing nitrification rates was dependent on N addition but not affected by the two typologies of zeolites tested. The outcomes of this study indicated the good compatibility of both natural and NH4+-enriched chabazite zeolite with DMPP. In particular, the application of NH4 +-enriched zeolites with DMPP is recommended to mitigate short-term N losses

ADSORBIMENTO DI GLIFOSATE ED AMPA IN SUOLI AGRICOLI

Immediately after application glyphosate is mostly adsorbed in the upper 2 cm of soils, and is then transported and adsorbed after few days in deeper soil horizons with concomitant increasing content of its metabolite aminomethylphosphonic acid (AMPA). This work confirmed previous studies, where Fe-oxides seem to play a major role in the adsorption of glyphosate and AMPA in soils:  the Chernozem featured lower contents of Fed and Feo, with consequently lower adsorption of glyphosate and AMPAas compared with the higher weathered Cambisol and Stagnosol.Immédiatement après l'application du glyphosate est surtout adsorbé dans les 2 cm supérieurs des sols, et est ensuite transporté et absorbé après quelques jours horizons profonds du sol avec un contenu croissant concomitante de son métabolite acide aminomethylphosphonic (AMPA). Ce travail confirme les études précédentes, où les oxydes de fer semblent jouer un rôle important dans l'absorption de glyphosate et d'AMPA dans les sols: le tchernoziom vedette des teneurs plus faibles de la Fed et Feo, avec par conséquent inférieur adsorption de glyphosate et d'AMPA par rapport à la plus altérée Cambisol et Stagnosol.Subito dopo l'applicazione il glifosate viene per lo più adsorbito nei primi 2 cm della parte superiore del suolo, per essere poi trasportato e assorbito nei giorni successivi in orizzonti più profondi del suolo con concomitante aumento del contenuto dell‘ acido aminomethylphosphonic metabolita (AMPA). Questo lavoro confermando studi precedenti, mostra come gli Fe-ossidi sembrano svolgere un ruolo importante nell‘assorbimento del glifosate ed AMPA nei suoli. Il Chernozemevidenzia contenuti più bassi di Fed e Feo, con conseguente minor assorbimento di glifosate e AMPA rispetto ai Cambisol e Stagnosol maggiormente interessati da fenomeni di alterazione

Soil aggregation, aggregate stability, organic carbon and nitrogen in different soil aggregate fractions under forest and shrub vegetation on the Loess Plateau, China

Revegetation has been reported as one of the most effective counter measures to reduce soil and water erosion on the Loess plateau in China. Soil aggregate stability and the distribution of organic carbon and nitrogen in different aggregate fractions would be affected by different plant communities. The objectives of this study were to elucidate the effects of different plant communities on soil aggregate stability and the distribution of organic carbon and nitrogen in different aggregate fractions in order to prove that the different plant covers enhance soil aggregate stability. Six kinds of soil samples under forest (Quercus liaotungensis, Populus davidiana, Pinus tabulaeformis, Bothriochloa, a 14 year abandoned land, and a 19 year bare fallow soil. Four kinds of soil samples under shrub land (the 24 year old Caragana Korshinskii Kom.; the 14 year old C Korshinskii Kom., 3 year old abandoned grazing land and traditional slope cropland which is claimed by the farmers for production with very low fertilizers) were collected from the hilly-gully area on the Loess Plateau, which was divided into 0-10 cm and 10-20 cm. We investigated soil aggregate stability and soil aggregate fractions by ultrasonic fractionation (USAS), and the distribution of organic carbon and nitrogen in different fractions under forest and afforested land, as key indicators for soil remediation through revegetation. The results showed that soil organic carbon (Corg) and total nitrogen (Nt) were strongly increased under forest and artificial shrub land compared to cropland and bare fallow land and were higher in the surface layers (0-10 cm) than in the subsurface (10-20 cm). Soil aggregate stability (SAS) was quite low under bare fallow land and cropping land soils, in comparison with the 4 forest communities. The three main fractions of soil aggregates, obtained by ultrasonic fractionation, were <63 mu m, 63-100 mu m and 100-250 mu m, which represented approximately 60%, 10% and 10%, respectively. In all land uses, macro-aggregates, 1000630 mu m > 630-250 mu m had a higher Corg content than micro-aggregates, 250-100 mu m > 100-63 mu m >> 63 mu m. In comparison to cropland and bare fallow land, forest and artificial shrub can protect and enhance the Corg, Nt and soil aggregate stability. The higher C:N ratio of macro-aggregate fractions indicates a rapid turnover of soil organic carbon in the top soil of forest sites and even on bare fallow and crop land. The narrow range of C:N ratio in micro-aggregates indicates that soil organic carbon in micro-aggregates is more stable than that in the macro-aggregates. We concluded that revegetation of eroded soils accelerates soil remediation and rehabilitation. (C) 2010 Elsevier B.V. All rights reserved

Soil microbial parameters and stability of soil aggregate fractions under different grassland communities on the Loess Plateau, China

Over-grazing and large-scale monocultures on the Loess plateau in China have caused serious soil erosion by water and wind. Grassland revegetation has been reported as one of the most effective counter measures. Therefore, we investigated soil aggregation, aggregate stability and soil microbial activities as key parameters for soil remediation through grassland revegetation. The results showed that soil microbial biomass carbon (Cmic) and microbial biomass nitrogen (Nmic) increased under revegetated grass communities compared to cropland and overgrazed pastures and were higher in surface layers (0-10 cm) than in the subsurface (10-20 cm). Although there are variations between the four investigated grassland communities, their values were 10 to 50 times higher in comparison to the cropland and overgrazed pastures, similar to the increase in soil enzyme activities, such as beta-glucosidase and beta-glucosaminidase. Soil aggregate stability (SAS) showed clear differences between the different land uses with two main soil aggregate fractions measured by ultra sound: < 63 mu m and 100-250 mu m, with approximately 70% and 10% of the total soil volume respectively. We also found positive correlations between SAS and soil microbial parameters, such as Cmic, Nmic, and soil enzyme activities. From this, we concluded that revegetation of eroded soils by grasses accelerates soil rehabilitation

The Biological Origins of Soil Organic Matter in Different Land-Uses in the Highlands of Ethiopia

In the Ethiopian highlands, clearance of Afromontane dry forest and conversion to crop and grazing land lead to land degradation and loss of soil organic matter (SOM). Eucalyptus is often grown on degraded soils, and this results in the partial recovery of soil carbon stocks. The aim of this work was to assess the biological sources of SOM in this land-use sequence. In top-soils (0–10 cm) of four land-use systems, namely remnant natural forest, eucalyptus plantation, cropland, and grazing land, in the Ethiopian highlands, the origin of SOM was investigated. For this, a sequential extraction method was used, involving a solvent extraction, base hydrolysis, and a subsequent CuO oxidation. In these extracts, biomarkers (molecular proxies) were identified to characterize the SOM of the soil of the four land-uses. Putative lipid monomers of leaf, root, and microbial degradation products suggest that root inputs and microbial inputs dominate in SOM of all the land-uses, except grazing land. The ratios of syringyls, vanillyls, and cinnamyls showed that non-woody angiosperm plants were the predominant source for lignin in eucalyptus, cropland, and grazing land soil. In the soils of the natural forest, lignin originates from both woody angiosperms and woody gymnosperms. Our study shows the importance of root and microbial inputs in the formation of SOM, but also that, in the natural forest, legacies of previous forest cover are present

Sorption of nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) in soils amended with natural zeolites and biochar

Innovative agricultural practices increasingly include the application of natural zeolite-rich rocks (NZ, zeolitites) or biochar (BC) to soils to improve their characteristics, crop yield and mitigate the effect of climate change. Amendment practices with pre-NH4+ enriched zeolites (CZ) and BC have recently shown to accelerate nitrification, and thereby N losses via NO3 leaching and emission of N2O, a potent greenhouse gas (GHG). The simultaneous use of nitrification inhibitors (NI) could be a useful mitigation strategy by maintaining the soil physico-chemical improvements by zeolites and BC. The efficacy of NIs relies on their availability to soil microbial biomass to inhibit/reduce ammonia oxidation. The main objective was to study sorption of inhibitor molecules on soils amended with NZ/CZ and BCs. Sorption of NIs is likely affected by the soil amendments since they are characterized by a variety of physico-chemical properties. For example, zeolites show high cation exchange capacity (CEC), molecular sieving and reversible dehydration, while biochar also shows high CEC, high organic carbon content (OC) compared to zeolites, and hydrophobicity varying with feedstock and pyrolysis temperature. The sorption behavior of NI was tested in soil added with 10% w/w of NZ and CZ and in pure NZ and CZ. BC obtained from different feedstocks and pyrolysis temperatures were added at 3 % w/w and at 1 % w/w for comparing the effects of application rate. The NI 3,4-dimethylpyrazole phosphate (DMPP) was chosen as model NI because of several favorable characteristics, such as the very low application rates (< 1 % of the N added) and absence of toxicity for soil fauna and crops. Sorption was studied using 6 different concentrations of DMPP (1, 10, 50, 100, 200, 500 mg L-1) in phosphate buffer (pH 7) and containing 3 mM NaN3. Concentrations were measured by HPLC analysis, and isotherms fitted using Langmuir equation. Both amendments significantly increased soil CEC but contrasting effects were observed concerning DMPP sorption: pure CZ and NZ showed a very low sorption of DMPP, thus zeolites decrease its sorption in the soil while BC generally increased DMPP sorption. The fact that DMPP is neutral in the studied pH range suggest that no CEC processes occurred between the employed amendments and DMPP but that probably the sorption process was driven by OC, which is known to be one of the primary carriers for DMPP sorption in soils. In this light, one of the main differences between zeolites and BC consist indeed in their OC content, which is very low in NZ/CZ and high in BC. The low OC in zeolite amendments is suggested to cause the low sorption of DMPP while higher DMPP sorption in soils amended with BC, can be due to the additional OC, however the differences in sorption with pyrolysis temperature are very likely related to hydrophobic interactions. Our results suggest higher availability of DMPP in zeolite amended soils than in BC amended soils, due to higher sorption in the latter

The Biological Origins of Soil Organic Matter in Different Land-Uses in the Highlands of Ethiopia

In the Ethiopian highlands, clearance of Afromontane dry forest and conversion to crop and grazing land lead to land degradation and loss of soil organic matter (SOM). Eucalyptus is often grown on degraded soils, and this results in the partial recovery of soil carbon stocks. The aim of this work was to assess the biological sources of SOM in this land-use sequence. In top-soils (0–10 cm) of four land-use systems, namely remnant natural forest, eucalyptus plantation, cropland, and grazing land, in the Ethiopian highlands, the origin of SOM was investigated. For this, a sequential extraction method was used, involving a solvent extraction, base hydrolysis, and a subsequent CuO oxidation. In these extracts, biomarkers (molecular proxies) were identified to characterize the SOM of the soil of the four land-uses. Putative lipid monomers of leaf, root, and microbial degradation products suggest that root inputs and microbial inputs dominate in SOM of all the land-uses, except grazing land. The ratios of syringyls, vanillyls, and cinnamyls showed that non-woody angiosperm plants were the predominant source for lignin in eucalyptus, cropland, and grazing land soil. In the soils of the natural forest, lignin originates from both woody angiosperms and woody gymnosperms. Our study shows the importance of root and microbial inputs in the formation of SOM, but also that, in the natural forest, legacies of previous forest cover are present