Landscape-scale variability of nitrogen fixation by pea and the availability of its residue-N for the succeeding crop

Non-Peer ReviewedThe main objectives of this study were to estimate the variability in N2-fixation across a large field and to determine whether the availability of legume residue-N to the succeeding crop was controlled by position of incorporation. In 1991, a field was selected near Blaine Lake, Saskatchewan and a 130 x 130 m grid composed of 169 sample sites was laid out. Six landform elements (upper and lower level, divergent and convergent shoulders and footslopes) were identified and the variability of N2-fixation (15N-isotope dilution) by pea was determined for 60 sites (six landforms x 10 replicates). At each site, the 15N-labeled pea residue was incorporated in a nearby unlabeled area in the spring of 1992. The percent N derived from N2-fixation (% Ndfa) by pea had a median of 57%. A difference in% Ndfa between landforms was observed with the highest% Ndfa at the divergent footslopes (69) and the lowest on the convergent shoulders (28). The total N2 fixed (seed+residue) did not show a landform effect and had a median of 57 kg N ha-1. The total N in pea residue (21-30 kg N ha-1) translated into C:N ratios ranging from 37-56. In 1992, landform differences for grain yield of spring wheat were present. Grain yield ranged from 1160 kg ha-1 on convergent footslopes to 1880 kg ha-1 on divergent shoulders. Due to the early frost, the median harvest index was low (0.24). The% Ndfr (N derived from residue) and% RUE (residue use efficiency) in the wheat grain and residue suggested that almost none of the pea residue-N had become available for wheat. The main reasons for the low N availability of the residue were: 1) incorporation of the pea residue at time of seeding (potential net N-mineralization of the residue in the fall and spring was excluded), and 2) the below average temperatures and precipitation in 1992 which would have reduced soil microbial activity and therefore net N -mineralization

Yield of PB50 inoculated and phosphorus fertilized wheat

Non-Peer ReviewedFour locations in the Brown (Leader, Sceptre, Kindersley, and Gull Lake), two in the Dark Brown (Regina and Outlook (irrigated)), five in the Black (Blaine Lake, Dubuc, Glenavon, Langbank, and Star City), and two in the Dark Gray soil zones (Nipawin and Porcupine Plain) were selected in the spring of 1990. Selection of the locations was based upon the available P status in the soil. With a few exceptions, all locations required P fertilization. At each location, the experiment was carried out on fields that were either on summerfallow, cereal stubble or oilseed stubble, all in close vicinity to one another. The experiment was laid out as a randomized complete block design with the following treatments 1) Control, 2) PB50 only, 3) 11.2 kg/ha of P2O5, 4) PB50 + 11.2 kg/ha P2O5, 5) 22.4 kg/l1a of P2O5 and, 6) PB50 + 22.4 kg/ha P2O5, replicated four times. Nitrogen and in some cases P and S was applied at blanket rates when necessary. At all sites Katepwa spring wheat was used as the test crop. Crop yields (grain and grain+ straw) were determined and fluctuated widely among the 13 locations due to the variable precipitation received in 1990. At one site, a significant (P <0.05) P fertilizer response on grain yield was observed. Whereas significant responses did occur at other sites, it was not directly related to P fertilizer and/or PB50. At most of the sites, however, no P fertilizer and/or PB50 response was observed. The concentration of P in the tissue, sampled at the Feekes 2 to 3 stage, was found to be not significantly different between the various treatments at most of the sites tested. If a significant difference was observed, the P fertilizer application caused the increase in P concentration.With the exception of two sites, the average amount of kg P/ha removed from the field through the grain was less than the total amount of the full rate of applied P and at some sites, half or less P was removed

Rates of denitrification as influenced by irrigation

Non-Peer ReviewedThe rate of denitrification, using the acetylene blockage method, was determined before and after irrigation at two sites; at Birsay on a clay-loam soil and at Outlook on a sandy soil. At Birsay, 110 kg N/ha as urea was applied 10 days before seeding and an additional 4 kg N/ha as ammonium phosphate at time of seeding. At Outlook, 50 kg N/ha as ammonium nitrate was applied just before seeding. Before irrigation, the rate of denitrification at both sites was almost undetectable. A sharp increase in the rate, however, occurred at both sites within a few hours after irrigation (approximately 25 mm) and lasted for approximately 24 hrs and 12 hrs at Birsay and Outlook, respectively. At the time of maximum activity, the losses of N (N2O and N2) were estimated to be 50 g ha-1 hr-1 and 3 g ha-1 hr-1 at Birsay and Outlook, respectively. The total amount of N lost per irrigation cycle, due to denitrification, at Birsay and Outlook were calculated to be 730 g ha-1 and 21g ha-1, respectively. The difference in the amount of N2O evolution at the two sites is partially attributed to the difference in soil type. The water holding capacity at Outlook is lower as compared with the soil at Birsay. Subsequently, the degree of anaerobic conditions, a pre-requisite for denitrification, will be less at Outlook. A lag period of 20 hrs occurred between the application of water and the maximum evolution of N2O of incubated soil cores. This was determined by analyzing incubated soil cores repeatedly over a period of 48 hrs. As the increase in denitrification at Birsay lasted for 24 hrs after the application of water, the maximum rate of denitrification did occur under those field conditions at Birsay. At Outlook, however, where the increase in denitrification only lasted for 12 hrs, the maximum rate of denitrification was not obtained under the existing field conditions. There were 10 irrigation and 7 precipitation events which caused denitrification. According to the percentage of the landform elements and its proper denitrification activity, the total N lost per year at Birsay was estimated to be 120 kg ha-1

Yield of PB50 inoculated and phosphorus fertilized wheat

Non-Peer ReviewedFour locations in the Brown (Leader, Sceptre, Kindersley, and Gull Lake), two in the Dark Brown (Regina and Outlook (irrigated)), five in the Black (Blaine Lake, Dubuc, Glenavon, Langbank, and Star City), and two in the Dark Gray Soil Zones (Nipawin and Porcupine Plain) were selected in the spring of 1990. Selection of the locations was based upon the available P status in the soil. With a few exceptions, all locations required P fertilization. At each location, the experiment was carried out on fields that were either on summerfallow, cereal stubble or oilseed stubble, all in close vicinity to one another. The experiment was laid out as a randomized complete block design with the following treatments 1) Control, 2) PB50 only, 3) 11.2 kg/ha of P2O5, 4) PB50 + 11.2 kg/ha P2O5, 5) 22.4 kg/ha of P2O5 and, 6) PB50 + 22.4 kg/ha P2O5, replicated four times. Nitrogen and in some cases P and S was applied at blanket rates when necessary. At all sites Katepwa spring wheat was used as the test crop. Crop yields (grain and grain+ straw) were determined and fluctuated widely among the 13 locations due to the variable precipitation received in 1990. At one site, a significant (P <0.05) P fertilizer response on grain yield was observed. Whereas significant responses did occur at other sites, it was not directly related to P fertilizer and/or PB50. At most of the sites, however, no P fertilizer and/or PB50 response was observed. The concentration of P in the tissue, sampled at the Feekes 2 to 3 stage, was found to be not significantly different between the various treatments at most of the sites tested. If a significant difference was observed, the P fertilizer application caused the increase in P concentration. With the exception of two sites, the average amount of kg P/ha removed from the field through the grain was less than the total amount of the full rate of applied P and at some sites, half or less P was removed

Rates of denitrification as influenced by irrigation

Non-Peer ReviewedThe rate of denitrification, using the acetylene blockage method, was determined before and after irrigation at two sites; at Birsay on a clay-loam soil and at Outlook on a sandy soil. At Birsay, 110 kg N/ha as urea was applied 10 days before seeding and an additional4 kg N/ha as ammonium phosphate at time of seeding. At Outlook, 50 kg N/ha as ammonium nitrate was applied just before seeding. Before irrigation, the rate of denitrification at both sites was almost undetectable. A sharp increase in the rate, however, occurred at both sites within a few hours after irrigation (approximately 25 mm) and lasted for approximately 24 hrs and 12 hrs at Birsay and Outlook, respectively. At the time of maximum activity the losses of N (N2O and N2) were estimated to be 50 g ha-1 hr-1 and 3 g ha-1 hr-1 at Birsay and Outlook, respectively. The total amount of N lost per irrigation cycle due to denitrification at Birsay and Outlook were calculated to be 730 g ha-1 and 21 g ha-1, respectively. The difference in the amount of N2O evolution at the two sites is partially attributed to the difference in soil type. The water holding capacity at Outlook is lower as compared with the soil at Birsay. Subsequently, the degree of anaerobic conditions, a prerequisite for denitrification, will be less at Outlook. A lag period of 20 hrs occurred between the application of water and the maximum evolution of N2O of incubated soil cores. This was determined by analyzing incubated soil cores repeatedly over a period of 48 hrs. As the increase in denitrification at Birsay lasted for 24 hrs after the application of water, the maximum rate of denitrification did occur under those field conditions at Birsay. At Outlook, however, where the increase in denitrification only lasted for 12 hrs, the maximum rate of denitrification was not obtained under the existing field conditions. There were 10 irrigation and 7 precipitation events which caused denitrification. According to the percentage of the landform elements and its proper denitrification activity, the total N lost per year at Birsay was estimated to be 120 kg ha-1

Nitrogen accumulation by pea as affected by topography

Non-Peer ReviewedField peas grown under normal field conditions are exposed to variable soil and environmental conditions that will affect both crop yield and nitrogen (N) uptake. Topography and slope position may play an important role in governing soil and environmental factors that influence N accumulation. In 1991, a field experiment was initiated to examine the effects of landscape position on the yield and N accumulation by field pea (var. Marofat). A two-hectare site was located in the Black Soil Zone on land with gently sloping to roughly undulating slopes (2-5 %). Six landform elements were identified at the site location. The site was managed at a farm scale using typical cultural practices. Spring levels of inorganic nitrogen (NO3 + NH4) ranged from 19.0 to 57.4 kg/ha (0-60 cm depth). Differences in levels of inorganic nitrogen between landform elements were observed (p = 0.03). Volumetric moisture content of the soil (0-120 cm) was consistently highest in footslopes throughout the growing season. Water stress was not a limiting factor to plant growth in any landform until 50-55 days after planting. Total yield (seed + straw) of the pea crop ranged from 2310 to 8100 kg/ha while seed yield varied from 960 to 3940 kg/ha. Significant differences between landforms were detected for total yield (p = 0.02) but not seed yield. Seed nitrogen content ranged from 31-133 kg/ha but no differences were observed between landforms

Effect of wheat distillers dried grains with solubles or sugar beet pulp on prevalence of Salmonella enterica Typhimurium in weaned pigs

Salmonella enterica Typhimurium (ST) is of concern in the swine industry with relevance for animal health and consumer safety. Nutritional strategies might help to reduce ST infection and transmission. This study examined the potential of wheat (Triticum aestivum) distillers dried grains with solubles (DDGS) and sugar beet (Beta vulgaris) pulp (SBP) to alter intestinal microbial communities and ST shedding using a Trojan model. Weaned pigs (n = 105; 28.5 ± 3.5 d of age) were separated into 3 treatment groups (7 pigs/pen) and fed a wheat-based control diet or the control diet formulated with 15% wheat DDGS or 6% SBP inclusion. Following 12 d of diet adaptation, 2 pigs/pen were inoculated with 2 x 109 cfu ST, resistant to novobiocin and nalidixic acid. Fecal swabs were taken from infected pigs and pen-mates (contact pigs) for 9 d following challenge, enriched in nutrient broth for 24 h, and plated on selective media to determine prevalence of ST. The ranges of prevalence of ST in feces were from 90 to 100% in challenged pigs and 74 to 78% in contact pigs. No influence of treatment on rectal temperature and prevalence of ST in contact pigs were observed. Fifteen contact pigs were euthanized per treatment group on 9 and 10 d postchallenge to enumerate in intestinal contents (ileum, cecum, and proximal colon), Lactobacillus spp., Enterobacteriaceae, and Clostridium clusters I, VI, and XVIa by quantitative PCR (qPCR) and to determine ST prevalence by selective culture. No significant effects of diet were observed with respect to ST prevalence in feces, ileum, cecum, colon, and lymph nodes of contact pigs. Compared with the control diet, DGGS and SBP diets showed a trend towards increased (P < 0.1) number of Lactobacillus species in the cecum and colon. Although both wheat DGGS and SBP tended to increase the Lactobacillus spp. neither of the feed ingredients affected ST prevalence

CRISPR/Cas9-induced (CTG⋅CAG)n repeat instability in the myotonic dystrophy type 1 locus: implications for therapeutic genome editing

Myotonic dystrophy type 1 (DM1) is caused by (CTG⋅CAG)n-repeat expansion within the DMPK gene and thought to be mediated by a toxic RNA gain of function. Current attempts to develop therapy for this disease mainly aim at destroying or blocking abnormal properties of mutant DMPK (CUG)n RNA. Here, we explored a DNA-directed strategy and demonstrate that single clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-cleavage in either its 5′ or 3′ unique flank promotes uncontrollable deletion of large segments from the expanded trinucleotide repeat, rather than formation of short indels usually seen after double-strand break repair. Complete and precise excision of the repeat tract from normal and large expanded DMPK alleles in myoblasts from unaffected individuals, DM1 patients, and a DM1 mouse model could be achieved at high frequency by dual CRISPR/Cas9-cleavage at either side of the (CTG⋅CAG)n sequence. Importantly, removal of the repeat appeared to have no detrimental effects on the expression of genes in the DM1 locus. Moreover, myogenic capacity, nucleocytoplasmic distribution, and abnormal RNP-binding behavior of transcripts from the edited DMPK gene were normalized. Dual sgRNA-guided excision of the (CTG⋅CAG)n tract by CRISPR/Cas9 technology is applicable for developing isogenic cell lines for research and may provide new therapeutic opportunities for patients with DM1

CC-studio : hoge verwachtingen, maar kansen voor innovatie

In dialog, Danny van Kessel and Gerald Lindner, both designers at cc-studio, discuss the opportunities for innovation when working for private clients