Effects of Selcote® ultra and sodium selenate (laboratory versus commercial grade) on selenium concentration in feed crops

Field studies were conducted at two locations in P.E.I., Canada on cereals and forages on the effect of soil applications of Selcote® Ultra and on a comparison of sodium selenate (laboratory versus commercial grade) on selenium (Se) concentration in plant tissue. Soil at both locations was sandy loam in texture and the soil pH ranged from 5.8 to 6.0. The data showed that 5 g Se ha^‐1 added as Selcote® Ultra was adequate to raise the Se level in the first two cuts of forage tissue above the minimum required level of 100 ug kg^‐1. For cereals, 10 g Se was necessary to achieve the same level. The residual effect of 10 g Se ha^‐1 from Selcote® Ultra added in the first year maintained plant Se at >100 μg kg^‐1 in the second year in the first cut of alfalfa at one location and ryegrass at both locations. A comparison of selenate‐Se (laboratory vs commercial grade) showed that both sources at similar levels of Se fertilization were equally effective in enriching barley grain with Se with no significant differences. Addition of 10 g Se ha^‐1 rate was necessary to ensure adequate Se (>100 ug kg^‐1) concentration in the ensuing graia Increasing rates of Se increased the Se levels in grain. Selenium concentrations were much higher in the barley boot stage vegetative tissue than in the grain. Results of this study showed that only 5 g Se ha^‐1, as Selcote® Ultra, is needed to maintain adequate Se in forages. The laboratory and commercially available selenate‐Se sources were equally effective in raising Se in barley.     

Effects of fertilizer timing and placement on grain yield and leaf nutrients of sole‐crop cowpeas (V. unguiculata) in Sierra Leone

Abstract

Effects of fertilizer timing and placement on the grain yield and leaf nutrients of uninoculated sole‐crop cowpeas in two experiments during the minor cropping season on Njala upland soil of Sierra Leone were studied. Timing and placement and their interaction had no significant effects on grain yield. Placement affected highly significantly lamina Mg, Cu and Co and significantly lamina N and Ca. Placement and timing x placement interaction affected highly significantly petiole N and petiole P respectively. Timing affected highly significantly petiole N, which decreased as fertilizer application was delayed. The spectrum of nutrient distribution in both lamina and petiole was decidedly different. Multiple regression studies indicated that variability in only petiole Mg, Cu and Co significantly contributed to grain yield variability. By the introduction of 15 nutrients (6 lamina and 9 petiole) after examining the linear regression coefficients into a composite multiple regression study, lamina Ca, petiole Fe and petiole Co were selected as significant contributors to grain yield variability with marked improvement in R². Removal of the effects of the correlated variables produced significances in the effects of fertilizer placement and timing x placement interaction on grain yields.     

Effects of epigeic earthworm (Eisenia fetida) and arbuscular mycorrhizal fungus (Glomus intraradices) on enzyme activities of a sterilized soil–sand mixture and nutrient uptake by maize

A pot experiment was conducted to investigate the effect of epigeic earthworm (Eisenia fetida) and arbuscular mycorrhizal (AM) fungi (Glomus intraradices) on soil enzyme activities and nutrient uptake by maize, which was grown on a mixture of sterilized soil and sand. Maize plants were grown in pots inoculated or not inoculated with AMF, treated or not treated with earthworms. Wheat straw was added as a feed source for earthworms. Mycorrhizal colonization of maize was markedly increased in AM fungi inoculated pots and further increased by addition of epigeic earthworms. AM fungi and epigeic earthworms increased maize shoot and root biomass, respectively. Soil acid phosphatase activity was increased by both earthworms and mycorrhiza, while urease and cellulase activities were only affected by earthworms. Inoculation with AM fungi significantly (p?<?0.001) increased the activity of soil acid phosphatase but decreased soil available phosphorus (P) and potassium (K) concentrations at harvest. Addition of earthworms alone significantly (p?<?0.05) increased soil ammonium-N content, but decreased soil available P and K contents. AM fungi increased maize shoot weight and root P content, while earthworms improved N, P, and K contents in shoots. AM fungi and earthworm interactively increased maize shoot and root biomass through their regulation of soil enzyme activities and on the content of available soil N, P, and K.     

A new method to measure allyl isothiocyanate (AITC) concentrations in mustard—Comparison of AITC and commercial mustard solutions as earthworm extractants

Earthworms are target organisms both for scientists studying the biological component of soils and for farmers concerned with monitoring the quality of their soils. Different expellants are used to extract earthworms from the soil but differences in chemical properties and efficiency between commercial mustard and allyl isothiocyanate (AITC) solutions remain unknown. The objectives of this study were to compare (i) the concentration of irritating product (allyl isothiocyanate AITC) in two expellant solutions (diluted mustard or AITC solution) and (ii) their efficiency in extracting earthworms from the soil.AITC concentration was analyzed according to a new method, based on AITC solvent extraction and HPLC quantification, in one commercial mustard brand to assess its variability within and between batches of jars. According to mustard spiking with AITC standard solution, extraction recovery was estimated as 98 ± 2%. Earthworm field data were collected in spring 2012 in 22 cultivated fields located in east Île-de-France, comparing pure AITC to commercial mustard solutions. Species diversity, abundance and biomass of earthworms per plot were measured.We showed that AITC concentration in commercial mustard varied according to the use by date but not according to the batch. We thus recommend using the freshest mustard available from the same batch. Moreover, AITC solution was found to be about four times more concentrated in AITC than the commercial mustard solution. Despite this result, no significant differences were found in the efficiency of commercial mustard or AITC solutions to bring earthworms to the soil surface in terms of abundance, biomass or diversity. We thus discuss the advantage and drawbacks of using both expellants in the field.     

A simple wet chemical extraction procedure to characterize soil organic matter (Som): 3. Results of vegetation,crop litter,and forest litter in comparison to data as revealed with CPMAS 13NMR spectroscopy and pyrolysis‐field ionization mass spectroscopy

Abstract

Data on the organic matter composition of vegetation, crop litter, and forest litter of Oi (=L) horizons from several European locations available with the litter compound analysis (LCA) discussed in previous communications are presented. The wet chemical results are discussed in comparison to data as revealed by cross polarization magic angle spinning carbon‐13 nuclear magnetic resonance spectroscopy (CPMAS ¹³C‐NMR) and pyrolysis‐field ionization mass spectrometry (Py‐FIMS). The LCA of vegetation, crop litter, and forest litter provides much detailed information about the chemical composition of extractable organic matter. Normally, both CPMAS ¹³C‐NMR and Py‐FIMS confirm the wet chemical results. Our data suggest a moderate chemical variation between the fresh organic residue and the litter. NMR revealed structural information about the non‐extractable organic matter using a combination of wet chemical extraction and CPMAS ¹³C‐NMR of whole soil. In addition, Py‐FIMS identified specific SOM segments at a qualitative level.