Effect of P fertilization management on alfalfa forage production and on soil available P

Non-Peer ReviewedA field experiment designed to determine the effect of P fertilization on forage production of alfalfa seeded in pure stands or mixed with Russian Wildrye was started in 1997 on a Swinton Silt Loam at Swift Current. Phosphorus as triple superphosphate was applied either prior to seeding at rates of 20, 40 or 80 (P20, P40, and P80, respectively) or as annual mid-row band applications of 10, 20 or 40 kg P2O5/ha (A10, A20, and A40, respectively). The A40 treatment was the only fertilizer regime that consistently produced the highest forage yields and forage P concentration. While the P40 and P80 treatments produced the same forage yields as A40 in the first two years of the study, their forage yields declined thereafter. All P treatments increased forage P concentration, especially A40 that consistently produced the highest P concentration. In the last year, however the preplant treatments failed to increase P concentration. Cumulative P balances for the check and preplant treatments had identical negative slopes and intercepts proportional to the rate of P applied. Balances for the annual treatments had intercepts proportional to applied P; while the A10 treatment had a zero slope; A20 andA40 had positive slopes proportional to the application of P. The level of Olsen P in the soil followed a trend similar to that described for the balance

Why are tame hay yields declining in Saskatchewan?

Non-Peer ReviewedProvincial agricultural production statistics show that grain crop yields have generally increased over the past 35 years while tame hay yields peaked in 1980 and have since been in decline. Weather data from 16 sites across Saskatchewan for the April, May, and June (AMJ) period were examined to explain this decline. As expected, precipitation during AMJ was positively correlated to hay yield but temperature was not. Hay yield was subsequently expressed as water use efficiency (WUE) based on published annual mean hay yield and AMJ precipitation. The WUE exhibited a negative correlation to year since 1980 and to the harvested hay acreage per year. After de-trending both WUE and harvested hay acreage for the year effect, the residual variation in both variables was still negatively correlated. We propose that older and lower-yielding hay fields are being harvested more frequently over the last two decades to provide feed for a growing Saskatchewan beef cow herd. This suggests that forage extension efforts should focus on hay field rejuvenation and agronomic management for improved productivity

Barley after hay: grass matters!

Non-Peer ReviewedPerennial forage crops are not traditionally grown in crop rotations in the Brown soil zone for several reasons: i) they are slow to establish; ii) they require intensive tillage to terminate; and iii) they reduce yield of subsequent crops. Short-lived perennial forages that possess rapid establishment characteristics could be used for 3 years of hay production with easier rotation to an annual crop. An experiment seeded in 1998 at the Semiarid Prairie Agricultural Research Centre with three short-lived grasses grown in monoculture or with two alfalfa cultivars was terminated by herbicide or tillage in May 2002, and subsequently seeded to barley. Visual observations prior to stand termination indicated that slender wheatgrass (SWG) and Dahurian wildrye (DWR) ground cover had declined but intermediate wheatgrass (IWG) was generally over 90% of the original. Barley yield was 17 bu/ac on plots previously in IWG compared to 26 and 28 bu/ac on plots previously in DWR and SWG, respectively. IWG reduced straw yield, harvest index, and test weight compared to SWG and DWG. Grass mixtures with Beaver alfalfa yielded 30 bu/ac compared to 21 and 19 bu/ac for Nitro alfalfa and grass monocultures. Barley grown on previously Beaver alfalfa mixtures also had higher straw yield, harvest index, and test weight compared to that grown on plots from the other two mixtures. These preliminary results suggest that short-lived grasses (DWR and SWG) may fit in crop rotations better than longer lived species (IWG) and that inclusion of alfalfa may, in fact, increase subsequent barley yields in this semiarid region

Managing an annual legume green manure crop for fallow replacement in southwestern Saskatchewan

Non-Peer ReviewedSome scientists have suggested that in the Brown soil zone an annual legume green manure crop (GM) could be used as a partial-fallow replacement to protect the soil against erosion and increase its N fertility, particularly when combined with a snow trapping technique to replenish soil water used by the legume. We assessed this possibility by comparing yields, N economy, water use efficiency, and economic returns of hard red spring wheat (W) grown in rotation with Indianhead black lentil (i.e., GM-W-W) vs. that obtained in a F-W-W system. Further, we assessed whether a change in management of the GM crop (i.e., moving to earlier seeding and earlier turn-down) was advantageous to the overall performance of this practice. The study was conducted over 12 years (1988-99) on a loam soil at Swift Current, SK. (wheat stubble was left tall to trap snow, tillage was kept to a minimum, and the wheat was fertilized based on soil tests). When examined after 6 years, the results suggested that by waiting for full bloom of the legume (usually late July or early August) to maximize N2 fixation, soil water was being depleted to the detriment of yields of the following wheat crop. However, the change in management of the GM crop since 1994 has resulted in wheat yields following GM equalling those after fallow. It also produced a significant increase (after one rotation cycle) in grain protein and N yields of aboveground parts of wheat in the GM-W-W compared to the F-W-W system, and lead to a gradual decrease in fertilizer N requirements of wheat in the GM system in the last 6 years. These savings in N fertilizer, together with savings in tillage and herbicide costs for weed control on partial-fallow vs conventional-fallow areas, and higher revenues from the enhanced grain protein, more than offset the added costs for seed and management of the GM crop. Thus, our results imply that, with proper management and given sufficient time, an annual legume GMcereal rotation is a viable option for area producers

Quantitative changes in soil C over 17 years under minimum tillage, well fertilized crop rotations in the Brown Soil Zone

Non-Peer Reviewe

Effect of cropping frequency, wheat classes, and flexible rotations on yield, production, and nitrogen economy in a Brown Chernozem

Non-Peer ReviewedProducers in the semiarid Canadian prairies frequently summerfallow (F) to conserve water, control weeds, and to maximize soil N reserves; however, this practice often results in soil degradation. A crop rotation experiment was initiated in 1987 on a medium textured, Orthic Brown Chernozem at Swift Current, to determine the most ideal cropping frequency for this region and whether a fixed rotation such as fallow-wheat-wheat (F-W-W) would be more effective than flexible rotations in which fallowing is decided each spring based on criteria such as available soil water (if water), or the need to control perennial weed infestations (if weeds). The study also compares the production of traditional Canada Western Red Spring (CWRS) wheat class with the newer higher yielding (Hy), Canada Prairie Spring (CPS) wheat class. The rotations included F-W-W, F-W-W-W, F-Hy-Hy, Continuous wheat (Cont W), Cont W (if weeds), and Cont W (if water). Over the study period (1987-1998), weather conditions were generally favourable and yields were above average for this region. Canada Prairie Spring wheat out-yielded CWRS by 35% when grown on fallow and by 15% when grown on stubble; however, straw yields of the two wheat classes were similar on fallow and CPS was 7% less than CWRS on stubble. Harvest index (HI) averaged 45% for CPS and 40% for CWRS wheat. Grain N concentration averaged 25.5 g kg-1 for CWRS and 22.5 g kg-1 for CPS; straw N concentration averaged 4.0 g kg-1 for CWRS and 4.6 g kg-1 for CPS. Nitrogen yield for grain from CPS was 13% greater than from CWRS when grown on fallow, but class had no effect when wheat was grown on stubble. Nitrogen yield of straw was generally not affected by wheat class. Nitrogen yield of the above-ground plant parts generally mimicked grain N yield responses. Nitrogen harvest index (NHI) averaged 80% for both wheat classes, whether grown on fallow or stubble. On a rotation basis, F-W-W-W and Cont W (if weeds) produced 9% more grain than F-W-W, while Cont W (if water) produced 24% more grain, and Cont W and F-Hy-Hy produced 29% more grain than FW-W. Nitrogen production in the grain, straw and above-ground plant material was lowest in F-W-W, highest in Cont W, and intermediate for other rotations

Variation in agronomic and morphological traits among Russian Wildrye accessions

Russian wildrye [Psathyrostachys juncea (Fischer) Nevski] accessions in the U.S. National Plant Germplasm System have not been adequately characterized for agronomic and morphological traits. Such characterization would be helpful in development of improved cultivars. Objectives of this study were to (i) measure consistency of dry-matter and seed yields as well as plant height and vigor of 65 Russian wildrye accessions and four cultivars at three diverse test sites, (ii) characterize phenotypic diversity among these accessions using duster analysis, and (iii) define needs for future evaluation and collection of Russian wildrye germplasm. Field tests were conducted at Logan, UT; Mandan, ND; and Swift Current, Saskatchewan, Canada. Dry-matter and seed yields were not consistent among accessions and cultivars at the three locations, and testing at each location was necessary to identify accessions that were best suited to a specific location. Variance component estimates were small and of little consequence for accession x year interaction effects. The 69 entries were grouped into 10 clusters based on multivariate analysis of 17 classification variables. Accessions in Cluster 3 averaged well above the overall test mean for dry-matter yield, seed yield, and plant vigor and have high utility in plant breeding programs in North America. Only four accessions had high levels of resistance to Septoria spraguei Uecker & J.M. Krupinsky, an important foliar disease. Accessions from a defined geographic area tended to cluster, but some accessions from a particular area were spread among several clusters. This emphasizes the value of sampling diverse collection sites within a defined geographic area

Variation in mineral concentration and grass tetany potential among Russian Wildrye accessions

Grass tetany or hypomagnesemic tetany in cattle (Bos taurus) is caused by an imbalance of K, Ca, and Mg in the diet. Indications of grass tetany range from reduced milk yield or weight gain to severe convulsions and death. The risk of grass tetany dramatically increases when the K/(Mg + Ca) ratio of forage exceeds 2.2, especially for dams during early lactation. Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski], a valuable forage species, has ratios well above this level. Our objectives were to determine the mineral concentration and ratio values for 65 accessions of Russian wildrye to select germplasm sources with low tetany ratio and to determine the effects of year, location, and their interactions with accessions. Seedlings of each accession and two checks, Syn A and Mankota, were established in replicated space-plant nurseries at Logan, UT, Mandan, ND, and Swift Current, Saskatchewan, Canada. Years-within-location effects generally produced the largest variance component, while the accession variance was larger than location x accession and location X accession x year interaction variances for K, Ca, Mg, KJ(Mg + Ca) ratio, and Reduced Tetany Potential (RTP) index. Selection for these traits in Russian wildrye germplasm will require multiple years to characterize adequately accessions, breeding lines, or synthetics. The K/(Ca + Mg) ratio of the accessions tested ranged from 2.2 to 3.0 when averaged across sites and years for V4 growth stage. A similar range of ratio values and ranking of the accessions was observed at the E2 growth stage. The three tetraploid accessions evaluated were among the five accessions with the highest tetany ratios. Previously reported forage yield and seed yield means were significantly correlated with K, Mg, and N concentrations and K/(Ca + Mg) ratio. The RTP index was not correlated with forage yield, seed yield, or N concentration. Therefore, selection in Russian wildrye should be based on increased RTP index rather than K concentration or K/(Ca + Mg) ratio to avoid concomitant unintentional selection of reduced forage yield and seed yiel

Determination of two-photon exchange amplitudes from elastic electron-proton scattering data

Using the available cross section and polarization data for elastic electron-proton scattering, we provide an extraction of the two-photon exchange amplitudes at a common value of four-momentum transfer, around Q^2 = 2.5 GeV^2. This analysis also predicts the e^+ p / e^- p elastic scattering cross section ratio, which will be measured by forthcoming experiments.Comment: 4 pages, 5 figures, updated error analysi

Russian wildrye nutritive quality as affected by accession and environment

High-quality forage for spring and fall grazing is an important need of ranchers in the Northern Great Plains and Intermountain-West regions of the United States of America and in the prairie provinces of Canada. Russian wildrye [Psathyrostachys juncea (Fischer) Nevski] has been used to meet this grazing need, especially in Canada. However, its use has probably been limited by its reputation for seedling establishment difficulties and scattered reports of grass tetany. The purpose of this research was to characterize the variation in nutritive quality of Russian wildrye accessions used in a multi-location grass tetany project, to access the effect of environment on quality components, and to determine the relationship between forage nutritive quality components and entities associated with grass tetany. Sixty-seven Russian wildrye accessions from the US National Plant Germplasm System were established in spaced-plant nurseries at Logan,UT, Mandan, ND, and Swift Current, SI(, Canada. Plants were sampled at two stages of development over 2 yr. Location, year, and stage of development effects were significant (P < 0.01) for in vitro true dry matter digestibility (IVDMD), crude protein (CP), and neutral detergent fiber (NDF). At the early stages of development used in this study the range in nutritive quality traits among entries was rather narrow. Relatively high positive correlation coefficients between K and IVDMD, and K and CP suggest that breeding for higher nutritive quality may also produce a more tetany-prone forage, because high K concentration is usually associated with grass tetany. On the other hand, Mg concentrations were also highly correlated with IVDMD and CP, and higher Mg concentrations would be beneficial in preventing grass tetany. The K/(Mg + Ca) ratio, which has been suggested as an indicator of grass tetany, was only moderately related to IVDMD, CP, and NDF