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In Côte d’Ivoire, smallholder farmers cultivate cassava on poor, highly weathered soils without improved varieties or fertilizer inputs. Land pressure combined with high demand result in premature harvests and low yields. Furthermore, subsistence agriculture limits the adoption of input-intensive technologies. This study aimed at identifying integrated soil fertility management systems for increasing cassava productivity and profitability in two locations in southern Côte d’Ivoire. The integrated technical interventions included improved cassava genotypes and modified spacing, legume intercropping, and application of fertilizer at moderate doses. Overall, an improved cassava variety (Yavo) generally out-yielded the other varieties at both sites. Legumes performed better at the higher soil fertility site and gave higher grain yield and biological nitrogen fixation in a 2 × 0.5 m cassava spacing compared to 1 × 1 m. The response of cassava to nutrient amendments varied between sites, suggesting the need for site-specific adaptations. Fertilizer application was essential to avoid cassava yield reduction upon legume intercropping as a result of competition for nutrients and N immobilization and delayed re-mineralization of legume residues. Growing legumes, however, substantially increased profitability. Hence, better synchronization of legume sowing, legume residue and fertilizer application in relation to cassava growth phases is needed. [ABSTRACT FROM AUTHOR]

The present study examines the effects of different fertilization treatments (chemical fertilization, farmyard manure, plant compost, and mycorrhiza-inoculated compost) on the soil fungi under a crop rotation of wheat (Triticum aestivum L.) and corn (Zea maysL.) in a long-term field experiment established in Mediterranean Turkey in 1996. Soil samples were collected in May, August, and October 2009. Soil pH, organic carbon, plant-available nitrogen and phosphorus, mycorrhizal colonization, and a series of biochemical markers (phospholipid and neutral lipid fatty acid [PLFA and NLFA] profiles, soil ergosterol content, and glomalin related soil protein [GRSP] as indicators of abundance of bacteria, saprotrophic, and arbuscular mycorrhizal [AM] fungi) were assessed. No significant difference was observed in soil organic C and plant available N in relation to long-term fertilization treatments, but plant available P in soil changed significantly in relation to the fertilization treatment used and the sampling season (between 11.5–33.8 mg · kg−1in spring, 10.4–28.6 mg · kg−1in summer, and 10.5–33.2 mg · kg−1in autumn). Mycorrhizal colonization patterns were similar for both plants. However, mycorrhiza-inoculated compost treatment exhibited higher root colonization (77.3%) over control (16.3%), chemical fertilization (10.0%), farmyard manure (19.3%), and plant compost (20.0%). No statistically significant change was observed in ergosterol content. The effect of long-term organic treatments on soil PLFA structure was statistically prominent; whereas seasonality only affected bacterial PLFAs. Organic fertilization increased GRSP (mean annual ranging from 0.91 to 2.46 mg · g−1total GRSP) but long-term annual mycorrhizal inoculation had no significant effect on the soil GRSP pool. [ABSTRACT FROM AUTHOR]

In Cuba there is a strong differentiation in types of farming systems that operate at very different levels of management intensity. The aim of this research was to characterize differences in soil quality caused by different agricultural management systems and the effects of seasonality on soil chemical and biological indicators within representative farming systems in Santa Clara municipality, Villa Clara Province, Cuba. Two state farms, two cooperative farms, and three private farms, all located on brown calcareous soils, which differed in soil management and technological complexity were selected. Soil samples from two fields of each farm were collected to a depth of 20 cm. Laboratory analysis were performed to determine physical (aggregate stability, plasticity, and permeability), chemical (pH and organic matter), and biological (dehydrogenase and β-glucosidase activities) indicators of soil quality. We found significant differences in soil quality among the three farming systems, which were most pronounced between private and state farms, with respect to physical soil properties (aggregate stability and plasticity) and the activity of enzymes. Seasonality also exerted an important influence on the activities of dehydrogenase and β-glucosidase, which were greater in the rainy season. As a conclusion, we can say that the differences in soil management between the farming systems were reflected in consistent differences in soil quality indicators, notably between the state and private farms. [ABSTRACT FROM AUTHOR]

Crop residues are an important component of N cycling in the agro-ecosystem. In this study, a loam soil was amended with cabbage residues and the N mineralization from soil organic matter and residues, as well as N uptake by Italian rye grass, were investigated. Four mineral fertilizer-residue combination treatments and two application times were tested in micro-plots. For uncropped micro-plots, application of residue resulted in higher soil mineral N content (43 mg N kg-1, 63 days post application) versus 30.5 mg N kg-1 for an unamended soil. Both bulked dry matter production and N uptake by the rye grass decreased in the order full mineral fertilizer > half mineral fertilizer + half residue > full residue applied 3 weeks before sowing > full residue applied at sowing, but the differences were more pronounced in the N uptake. Shoot N recovery from the applied residue (27.5-31.4%) was much smaller than that from the full fertilizer (70.2%), but was still considerable. Apparent net N mineralization from soil organic matter was significantly depressed in the treatments where mineral fertilizer was added. Cropping also reduced apparent net N mineralization, but this effect was reduced when residues were applied 3 weeks before sowing. Results showed that crop residues play an important role in crop production, in terms of obtaining comparable dry matter production to that of full mineral fertilizer application. Moreover, nitrogen supplied as residue is less liable for loss due to leaching during the growing season. The efficiency of crop uptake to residue-derived nitrogen could be increased by earlier application time. [ABSTRACT FROM AUTHOR]

Because the widely used ceramic cups are reported to release, adsorb, and filter dissolved nutrients from soil solution samples, inert cups made of poly(tetrafluoroethene) (PTFE) are frequently proposed as a more reliable alternative. A ceramic and a PTFE/quartz cup were compared with each other in this laboratory study. The PTFE/quartz cup was the most suited for pH measurements. Because only the ceramic cup samples both ammonium and nitrate in a satisfactory way, this cup type is recommended for nitrogen (N) balance studies. In most cases, the ceramic cup also performed better in sampling cations [sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+)] than the PTFE/quartz cup. Both cup types seemed inadequate to sample soil solution for aluminum (Al3+) determinations. The ceramic cups released chloride (Cl-) at low ion concentrations, but sulfate (SO42-) concentrations remained almost unaltered in the sample as compared to the solution outside the cup. In contrast, Cl- and SO42- were retained by the PTFE/quartz cups. The overall conclusion of this study is that PTFE/quartz cups have no clear advantages over the more widely used ceramic cups for use in ecological studies dealing with dissolved inorganic ions in the soil solution. [ABSTRACT FROM AUTHOR]

Compost and other organic amendments have been proven to improve the soil physical quality. In Flanders, vegetable, fruit and garden (VFG) wastes are collected selectively and composted. We studied the effects of the combined application of three different doses of VFG compost and cattle slurry and one treatment with only mineral N applied, during 9 years on a range of soil physical properties: aggregate stability, saturated hydraulic conductivity, hulk density, total pore volume and soil moisture retention. The organic amendments had a significantly beneficial impact (p<0.05) on all soil physical properties, except for the soil moisture retention which was hardly influenced by any of the treatments. The combined application of VFG compost and cattle slurry resulted in the best soil physical conditions. No significant differences were found in soil physical parameters between the unfertilized plots and plots that were fertilized with mineral N. [ABSTRACT FROM AUTHOR]

Renewed interest in temporal soil organic carbon (SOC) stock changes has stressed the importance of reliable methods for quantitative assessment of organic compound (OC) content. Particularly with the establishment of modern dry-combustion analyzers, which are replacing the traditional wet-oxidation methods, the need for correct relationships between both is of crucial importance for comparison of past and current SOC data in long-term SOC stock change studies. Dry combustion with a Variomax CNS-analyzer was the standard to evaluate three other methods for Belgian agricultural soils. Excellent linear relationships were found with the Walkey and Black method and the Springer and Klee method, whereas a Shimadzu TOC-analyzer slightly underestimated the OC content. Precision of the investigated methods was comparable and tended to be dependent on the sample size used for measurement. The OC oxidation efficiency of the most widely applied method of Walkey and Black for the soils in this study was very close to the generally accepted 75%. Mass loss on ignition at 800°C could be very well related to the soil OC content and the clay content. The traditional factor of 1.724 used to convert OC measurements to organic matter percentages is not valid for the investigated soils, which demonstrates that rather regional-specific factors (in this study 1.911) should be determined and adopted. [ABSTRACT FROM AUTHOR]

Organic farming is put forward as a sustainable alternative to the conventional way of farming. However, until now there has been practically no research on soil related aspects of organic farming in Flanders. Therefore, in this study, the carbon, nitrogen, sulphur and phosphorus status of the fields on organic farms was measured and was related to characteristics of the farms involved (land use, soil texture, management intensity and time since conversion to organic farming) and was, where possible, compared with the general soil fertility status of agricultural soils in Flanders. The SOC (soil organic carbon) contents tended to be larger in the fields of the organic farms studies than in conventional farming. This content was correlated positively with the management intensity of the fields. However, some of the organic fields still had rather low SOC contents. To increase this content organic farmers will need to apply more organic materials with large C:N and C:P ratios taking into account the strict current manure legislation. The mineral N contents on the organic farms measured in the period between 1 October 2003 and 15 November 2003, indicating the risk of nitrate leaching, were well below the average values of the different land use classes of conventional agricultural soils in East Flanders. The available P content of the organic fields was high to very high as is also the case for conventional agriculture in East Flanders and was strongly related to the management intensity. [ABSTRACT FROM AUTHOR]

At the moment, Hungarian agriculture is confronted with a certain duality as far as nutrients are concerned. On the one hand, national soil nutrient balances show substantial deficits, and on the other hand, agricultural nutrient use is responsible for a part of the nitrogen (N) and phosphorus (P) losses to the environment. To understand this duality and help optimize farm nutrient management, the farm gate N and P balances of 12 farms, representing a variety of Hungarian agriculture, were calculated for the year 2002. The farm gate N and P surpluses/deficits in the east of the country were lower than in the west. This was correlated with a lower fertilization rate. The low soil fertility level due to a prolonged period of low fertilization in combination with continuing nutrient deficits can lead to possible future reduction in crop yields. [ABSTRACT FROM AUTHOR]