Estimation of preliminary reference values for macro and micronutrients in ‘Valencia’ orange in Venezuela,by means of the compositional nutrient diagnosis system

The present study was aimed at developing preliminary reference values for foliar tissue for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) for `Valencia´ orange in Venezuela, using the Compositional Nutrient Diagnosis system (CND). References values were derived from a database comprising the nutrients concentrations and the yields of `Valencia´ orange trees (Citrus sinensis L. Osbeck) grafted on two different rootstocks, viz., Volkamer lemon (Citrus volkameriana Pasq.), and Cleopatra tangerine (Citrus reshni, Hort. ex. Tan). Cutoff values separating high- and low-yield sub-samples were estimated through modeling the cumulative variance ratio function versus yield relationships with the Boltzmann equation. For macronutrients, the norms developed were dependent upon the inclusion of the micronutrients concentrations in the calculations, and on the rootstocks. Care must thus be exercised, since nutrient indexes, and thus nutritional diagnosis, are based upon proper selection of such values.     

Yield,fruit quality and nutrient uptake of ‘Nabbut-Ahmar’ date palm grown in sandy loam soil as affected by NPK fertigation

A field experiment was conducted in 2011 and 2012 to study the effect of fertigation on yield, fruit quality and nutrient uptake of ‘Nabbut-Ahmar’ date palm cultivar grown in sandy loam soil. Three fertigation treatments were compared with traditional application. In traditional treatment (CT), the recommended dose [2300 g nitrogen (N), 1200 g phosphorus (P) and 1400 g/tree] was applied as a soil broadcast in three equal doses. The fertigation treatments, (T2), (T3) and (T4), represent all nitrogen, phosphorus and potassium (NPK) amounts of CT, 2/3 CT and 1/3 CT, respectively that were injected in twelve equal doses. The results showed that compared to CT, the fertigation treatments increased yield/palm by 41%, 31% and 18% for T3, T2 and T4, respectively. Beside the increase in yield, 33% and 66% of the applied fertilizers were saved by T3 and T4, respectively, compared with CT. Feritgation treatments had no negative impact on the overall fruit quality characteristics and even increased total soluble solids (TSS), soluble tannins and total phenols concentrations compared to the conventional fertilization. Availability of NPK increased by fertigation but without further increase in leaves and fruit. In conclusion applying 2/3 of the recommended dose of NPK fertilizers under dry land condition through fertigation maximize yield, quality and fertilizer use efficiency.     

Growth and cation absorption of some fruit‐vegetable crops grown on rockwool as affected by different cation ratios in the nutrient solution

In a series of experiments, cucumber, eggplant and sweet pepper were grown in rockwool with nutrient solutions of different ratios of potassium (K), calcium (Ca) and magnesium (Mg). The ratios between the anions in the nutrient solutions compared were the same. In addition to yield, the concentrations of cations in the root environment and in different plant tissues were determined.

The results show that the yield for eggplant fruits were strongly reduced by a low Mg level, while the yield of cucumbers seemed to be somewhat reduced by a low Ca supply. Sweet pepper yields were not affected among the cation ratios compared.

Relationships between cation contents in the root environment and cation contents in plant tissues were established. The correlation coefficients for these relationships were very high. The equations calculated for the various cations show remarkable differences. Regression coefficients and intercepts strongly depend on crop and plant part sampled. For Mg, it could be established that Ca strongly affected the uptake of Mg.     

Soil and sediment quality and composition as factors in the distribution of damage at the December 26, 2003, Bam area earthquake in SE Iran (M s = 6.6)

Background, aim, and scope

The rapid growth of the world’s population over the past few decades has led to a concentration of people, buildings, and infrastructure in urban areas. The tendency of urban areas to develop in sedimentary valleys has increased their vulnerability to earthquakes due to the presence of soft soil and sediment. Several earthquakes have clearly demonstrated that local soil and sediment conditions can have a significant influence on earthquake-induced ground motion and damage pattern, respectively. Many studies confirm the relationship between site effect and ground motion (Borcherdt in Bull Seismol Soc Am 60:29–61, 1970; Bouckovalas et al. in Geotech Geolog Eng (Historical Archive) 14(2):111–128, 1996; Fäh et al. in Seismology 1:87–10, 1997; Atakan et al. in Nat Hazards 15(2–3):139–164, 1997; Christaras et al. in Geodynamics 26(2–4):393–411, 1998; Raptakis et al. in Bull Earthquake Eng 2(3):285–301, 2004a; Raptakis et al. in Soil Dyn Earthq Eng 25:871–887, 2005; Marka et al. in Pure Appl Geophys 158:2349–2367, 2001; Marka et al. in Soil Dyn Earthq Eng 25(4):303–315, 2005; Importa et al. in Seismology 9(2):191–210, 2005; Tyagunov et al. in Nat Hazards 38:199–214, 2006; Lombardo et al. in Nat Hazards 38:339–354, 2006; Rayhani et al. in Geotech Geol Eng 21(1):91–100, 2008). In order to classify the suitability of the soil and subsurface sediment units for urban planning and compare their mechanical behavior with the non-uniform damage observed in the 2003 earthquake, we performed some geotechnical and geophysical analyses of soil and sediment samples collected from different locations in Bam City.

Methodology

Geophysical and geotechnical properties, such as grain size distribution, sorting, plasticity, Poison’s ratio, shear strength, compression index, permeability, and P and S wave velocities in soil and subsurface sediments, were measured. Maps (in GIS environment) and cross-sections were prepared for the study area.

Results

According to our observations, a great number of buildings were damaged in areas of the city where silty and clayey soils dominate, presenting very low permeability, low wave velocity together with high plasticity, and compressibility. In the study area, we recognized eight sediment types. Shear wave propagation velocities allowed for the identification of four seismic layers referred to as the surface layer, second layer, and third layer and seismic bedrock. We found that the damages observed in the Bam area were related to the physical and mechanical properties of the soil and subsurface sediment units. We also found that the soil thickness that was estimated by geophysical surveying shows a direct relationship with damage rate observations. Furthermore, we observed that landslide and qanat collapses have occurred in some areas where sand and silty sand soils and subsurface sediments dominate.

Discussion

The distribution of the damage shows a microzonation that is very serious in some points in the city along the main fault, especially where it is located on thick, fine, medium, and loose soil and sediments. In general, there is a discernable west to east increase in the damage across the city. The average level of destruction for the entire city was ~75%, while the eastern part of the city locally reached 100% destruction level. The major factors that influenced the damage and destruction in the Bam region were the distance of a given site from the seismic source, the quality of foundation soil and subsurface sediment, and the type of building. The Bam earthquake occurred on a single fault network comprising the Bam and Arg-e-Bam faults (Funning et al. in J Geophys Res 100(B09406):1–23, 2005). The sediments and soil of the area (unconsolidated silty sand and sandy gravel) belong to braided fluvial and alluvial facies. Most of the buildings near the epicenter area were old and constructed of mud bricks using mud cement.

Recommendations and perspectives

A combined sedimentological, geological, neotectonic, geotechnical, paleoseismological, and geophysical investigation in urban areas (especially in alluvial valleys) will give the detailed knowledge of the subsurface structure required for the accurate and precise seismic hazard assessments needed for effective earthquake protection planning. This paper shows that for the Bam situation, sedimentological data are required to provide an interpretive context for the geophysical data.     

Effects of rice cropping intensity on soil nitrogen mineralization rate and potential in buried ancient paddy soils from the Neolithic Age in China’s Yangtze River Delta

Purpose

Rice cropping density, rice cropping duration, and fertilization can affect soil nitrogen (N) supply, but rice cropping intensity (RCI) on soil N fertility is not fully understood, particularly for ancient paddy soils without N fertilization.

Materials and methods

Eight buried ancient paddy soils from the Neolithic Age in China’s Yangtze River Delta, and its parent material, and seven present paddy soils in the same fields were used to investigate the effects of RCI on soil nitrogen mineralization rate and potential. In the present study, concentration of phytolith of rice in soils was used to indicate the RCI.

Results and discussion

Soil N content was obviously greater in the buried Neolithic paddy soils than in the parent material. Total soil N increased with increasing phytolith from 5,200 to 60,000 pellets g^?1, but tended to decrease with increasing phytolith from 60,000 to 105,000 pellets g^?1. A possible reason for RCI-induced increase of soil N was due to biological N₂ fixation in the rice field because there was a significant negative relationship between total N and δ¹⁵N in the buried Neolithic soils. The mineralization rate constant (k) ranged from 0.0126 to 0.0485 d^?1 with an average of 0.0276 d^?1, which was similar to that of the parent material, but lower than those in the present paddy soils. The k value increased with increasing RCI in the Neolithic paddy soils. There was a significant positive relation between RCI and the percentage of cumulative mineralizable N in the 14 d of that within 103 d incubation.

Conclusions

Soil N content tended to increase with the increasing intensity of rice cropping and then decreased under the high intensity of rice cropping; the excessive high intensification of rice cropping could facilitate fast N mineralization (labile N) fraction in the cumulated mineralized N. The unfertilized paddy field could only meet soil N supply under the low intensification of cropping rice in the Neolithic Age. The N fertilization is necessary in order to improve soil fertility for sustaining the present high-yield rice production.     

Studies on microörganisms and their activities in soil Part. 1. Change of microflora induced by soil treatment,with special reference to the method of study

Introduction

Joffell described in his book “Pedology” that in the process of weathering, autotrophic organisms grow on the bare surface of rocks and their metabolic products contribute much to the weathering. Treub²⁾ observed also that the surface of volcanic ash was covered by the vigorous growth of algae in less than three years after the eruption of Krakatoa. From these statements it appears evident that microorganisms play an important part through the production of organic matter at the early period of soil formation. As soil-forming-process advances, however, microBrganisms are replaced by the higher chlorophyllbearing plants with regards to organic matter production in land, and they become more important in the decomposition of than in the production of organic matter.     

Changes in CO<Subscript>2</Subscript>, <Superscript>13</Superscript>C abundance,inorganic nitrogen, β-glucosidase,and oxidative enzyme activities of soil during the decomposition of switchgrass root carbon as affected by inorganic nitrogen additions

This study was conducted to investigate the effect of inorganic nitrogen (N) and root carbon (C) addition on decomposition of organic matter (OM). Soil was incubated for 200 days with nine treatments (three levels of N (no addition (N0) = 0, low N (NL) = 0.021, high N (NH) = 0.083 mg N g⁻¹ soil) × three levels of C (no addition (C0) = 0, low C (CL) = 5, high C (CH) = 10 mg root g⁻¹ soil)). The carbon dioxide (CO₂) efflux rates, inorganic N concentration, pH, and potential activities of β-glucosidase and oxidative enzyme were measured during incubation. At the beginning and the end of incubation, the native soil organic carbon (SOC) and root-derived SOC were quantified by using a natural labeling technique based on the differences in δ ¹³C between C3 and C4 plants. Overall, the interaction between C and N was not significant. The decomposition of OM in the NH treatment decreased. This could be attributed to the formation of recalcitrant OM by N because the potentially mineralizable C pool was significantly lower in the NH treatment (3.1 mg C g⁻¹) than in the N0 treatment (3.6 mg C  g⁻¹). In root C addition treatments, the CO₂ efflux rate was generally in order of CH > CL > C0 over the incubation period. Despite no differences in the total SOC concentration among C treatments, the native SOC in the CH treatment (18.29 mg C g⁻¹) was significantly lower than that in the C0 treatment (19.16 mg C g⁻¹).