Ethiopian agriculture has greater potential for carbon sequestration than previously estimated

More than half of the cultivation-induced carbon loss from agricultural soils could be restored through improved management. To incentivise carbon sequestration, the potential of improved practices needs to be verified. To date, there is sparse empirical evidence of carbon sequestration through improved practices in East-Africa. Here, we show that agroforestry and restrained grazing had a greater stock of soil carbon than their bordering pair-matched controls, but the difference was less obvious with terracing. The controls were treeless cultivated fields for agroforestry, on slopes not terraced for terracing, and permanent pasture for restrained grazing, representing traditionally managed agricultural practices dominant in the case regions. The gain by the improved management depended on the carbon stocks in the control plots. Agroforestry for 6-20 years led to 11.4 Mg ha^-1 and restrained grazing for 6-17 years to 9.6 Mg ha^-1 greater median soil carbon stock compared with the traditional management. The empirical estimates are higher than previous process-model-based estimates and indicate that Ethiopian agriculture has greater potential to sequester carbon in soil than previously estimated.

A Simple Dynamic Model of Soil Test Phosphorus Responses to Phosphorus Balances

Soil test P (STP) concentration indicates whether annual P applications can be expected to give yield increases and can also indicate an elevated risk of P mobilization and potential for P transfer to surface waters and groundwater from a particular field. Changes in STP with time thus project agronomic benefits and environmental risks of different P use strategies. To predict STP changes with time, we constructed a simple dynamic model for which the input variables are P balance and initial STP. The model parameters (soil type-specific constants) were fitted using data originating from 44 P fertilizer experiments with different P rates. Model performance was evaluated using independent data sets that either had reasonably accurate input values ( = 103) or were obtained from farmers through interviews ( = 638). The simulations were in agreement with measured STP changes for both evaluation data sets when fittings were performed separately for four main soil types (clays, silts, coarse mineral soils, and organic soils). Statistical analysis confirmed that the model captured the trends in STP (NHOAc test) with acceptable accuracy and precision, with of 0.83 and 0.66 for the data with more accurate input and for farmer interview data, respectively; the corresponding model efficiency statistics were 0.88 and 0.66. The model is not restricted to use with one soil test, as fittings for several different types of soil tests can be generated. In this study, we fitted the model for Olsen P data retrieved from the literature. Agronomic use of the model includes evaluation of P use strategies, e.g., when a certain STP level is targeted or when long-term economy of P use is calculated. In an environmental context, the model can be used to predict STP changes with time under variable P balance regimes, which is essential for realistic assessment of changes in the potential for dissolved P losses.

Tillage and crop residue management methods had minor effects on the stock and stabilization of topsoil carbon in a 30-year field experiment

We studied the effects of tillage and straw management on soil aggregation and soil carbon sequestration in a 30-year split-plot experiment on clay soil in southern Finland. The experimental plots were under conventional or reduced tillage with straw retained, removed or burnt. Wet sieving was done to study organic carbon and soil composition divided in four fractions: 1) large macroaggregates, 2) small macroaggregates, 3) microaggregates and 4) silt and clay. To further estimate the stability of carbon in the soil, coarse particulate organic matter, microaggregates and silt and clay were isolated from the macroaggregates. Total carbon stock in the topsoil (equivalent to 200 kg m(-2)) was slightly lower under reduced tillage (5.0 kg m(-2)) than under conventional tillage (5.2 kg m(-2)). Reduced tillage changed the soil composition by increasing the percentage of macroaggregates and decreasing the percentage of microaggregates. There was no evidence of differences in the composition of the macroaggregates or carbon content in the macroaggregate-occluded fractions. However, due to the higher total amount of macroaggregates in the soil, more carbon was bound to the macroaggregate-occluded microaggregates in reduced tillage. Compared with plowed soil, the density of deep burrowing earthworms (Lumbricus terrestris) was considerably higher under reduced tillage and positively associated with the percentage of large macroaggregates. The total amount of microbial biomass carbon did not differ between the treatments. Straw management did not have discernible effects either on soil aggregation or soil carbon stock. We conclude that although reduced tillage can improve clay soil structure, generally the chances to increase topsoil carbon sequestration by reduced tillage or straw management practices appear limited in cereal monoculture systems of the boreal region. This may be related to the already high C content of soils, the precipitation level favoring decomposition and aggregate turnover in the winter with topsoil frost.

Phosphorus in manure and sewage sludge more recyclable than in soluble inorganic fertilizer

Phosphorus (P) flow from deposits through agriculture to waterways leads to eutrophication and depletion of P reserves. Therefore, P must be recycled. Low and unpredictable plant availability of P in residues is considered to be a limiting factor for recycling. We identified the determinants for the plant-availability of P in agrifood residues. We quantified P in Italian ryegrass (Lolium multiflorum) and in field soil fractions with different plant availabilities of P as a response to manure and sewage sludge with a range of P capture and hygienization treatments. P was more available in manure and in sludge, when it was captured biologically or with a moderate iron (Fe)/P (1.6), than in NPK. Increasing rate of sludge impaired P recovery and high Fe/P (9.8) prevented it. Anaerobic digestion (AD) reduced plant-availability at relevant rates. The recovery of P was increased in AD manure via composting and in AD sludge via combined acid and oxidizer. P was not available to plants in the sludge hygienized with a high calcium/P. Contrary to assumed knowledge, the recyclability of P in appropriately treated residues can be better than in NPK. The prevention of P sorption in soil by organic substances in fertilizers critically enhances the recyclability of P.

Declining trend of carbon in Finnish cropland soils in 1974-2009

Soil organic matter not only affects soil properties and productivity but also has an essential role in global carbon (C) cycle. We studied changes in the topsoil C content of Finnish croplands using a dataset produced in nationwide soil monitoring. The monitoring network consisting of fields on both mineral and organic soils was established in 1974 and resampled in 1987, 1998, and 2009. Over the monitoring period from 1974 to 2009, cultivated soils showed a continuous decline in C concentration (g kg(-1) ). In organic soils, C concentration decreased at a mean rate of 0.2-0.3% yr(-1) relative to the existing C concentration. In mineral soils, the relative decrease was 0.4% yr(-1) corresponding to a C stock (kg m(-2) ) loss of 220 kg ha(-1)  yr(-1) . The change in management practices in last decades toward increasing cultivation of annual crops has contributed to soil C losses noted in this study. The results, however, suggest that the C losses result partly from other processes affecting cultivated soils such as climatic change or the continuing long-term effect of forest clearance. We estimated that Finnish cropland soils store 161 Tg carbon nationwide in the topmost 15 cm of which 117 Tg is in mineral soils. C losses from mineral soils can therefore total up to 0.5 Tg yearly.

The glycaemic and C-peptide responses of foods rich in dietary fibre from oat, buckwheat and lingonberry

Dietary fibre has a beneficial effect on metabolic syndrome, e.g. by influencing the absorption of glucose. The source and structure of fibre affect the glucose response. In this study, the glycaemic and insulinaemic response to oat bread, oat bread with lingonberry fibre, oat-buckwheat bread and buckwheat porridge were tested in a small-scale clinical study (KHSHP E514/09). Nine healthy volunteers consumed test foods after overnight fasting. Serum glucose and C-peptide levels were determined by colorimetric and ELISA methods, respectively, from samples taken at seven time points during 120 min. The mean glycaemic and C-peptide indexes (C-pepIs) were 32 and 100 for oat bread, 47 and 119 for oat-lingonberry fibre bread, 58 and 105 for oat-buckwheat bread and 71 and 77 for buckwheat porridge. Similar to rye, buckwheat porridge having a relatively high glycaemic index (GI) tended to have a low C-pepI. Buckwheat and lingonberry fibres provide new alternatives for low GI foods.

In vitro maturation supplements affect developmental competence of bovine cumulus-oocyte complexes and embryo quality after vitrification

Oocyte quality affects subsequent embryo development and quality. We examined the impact of bovine oocyte in vitro maturation (IVM) conditions on subsequent embryo yield, quality and cryosurvival. Cumulus-oocyte complexes (COCs) were sampled for cytological and gene expression analysis after IVM in TCM199 supplemented with 10% fetal bovine serum (FBS), 4 mg/ml of fatty-acid-free bovine serum albumin (FAFBSA), 4 mg/ml of polyvinylpyrrolidone (PVP), FAFBSA with epidermal growth factor (EGF, 100 ng/ml) and insulin-like growth factor 1 (IGF-I, 100 ng/ml) (FAFBSAGF), PVP with EGF and IGF-I (PVPGF) or PVP with single strength BME and MEM amino acids (PVPAA). The remaining COCs were fertilized. On day 7 (IVF=day 0) quality 1 blastocysts were vitrified or analyzed for glucose transporter 1 (Glut-1) expression levels. The remaining blastocysts (days 7-9) were evaluated for morphology and total cell counts. After warming, survival and hatching rates were evaluated followed by total cell counts and Glut-1 expression levels. Only PVPGF IVM resulted in embryo production rates comparable to those recorded with FBS IVM. Growth factors with FAFBSA and amino acids with PVP reduced embryo production rates whereas the effect of the growth factors with PVP was negligible. Insulin-like growth factor 2 binding protein 3 (IGF2BP3) and beta cell translocation gene 4 (BTG4) were revealed as potential candidates for oocyte developmental competence, and secreted protein, acidic and rich in cysteine (SPARC) for cumulus cell expansion. There were no differences among treatments in hatching rates of vitrified embryos after warming. However, total cell numbers and Glut-1 expression levels at 72 h were affected.

Fungal-mediated multitrophic interactions--do grass endophytes in diet protect voles from predators?

Plant-associated micro-organisms such as mycotoxin-producing endophytes commonly have direct negative effects on herbivores. These effects may be carried over to natural enemies of the herbivores, but this has been rarely explored. We examined how feeding on Neotyphodium endophyte infected (E+) and endophyte free (E−) meadow ryegrass (Scherodonus pratensis) affects body mass, population size and mobility of sibling voles (Microtus levis), and whether the diet mediates the vulnerability of voles to least weasel (Mustela nivalis nivalis) predation. Because least weasels are known to be olfactory hunters, we also examined whether they are able to distinguish olfactory cues of voles fed on E+ and E− diets. Neither body mass of voles nor population size differed between diets. However, contrary to our prediction, least weasels preyed more often on voles fed with E− grass than on voles fed with E+ grass. The mobility of voles fed on E+ grass was reduced compared to voles fed on E− grass, but this effect was unrelated to risk of predation. Least weasels appeared unable to distinguish between excrement odours of voles between the two treatments. Our results suggest that consumption of endophytic grass is not directly deleterious to sibling voles. What's more, consumption of endophytes appears to be advantageous to voles by reducing risk of mammalian predation. Our study is thus the first to demonstrate an effect of plant-associated microbial symbionts on herbivore-predator interactions in vertebrate communities.

Effects of serum-free in vitro maturation of bovine oocytes on subsequent embryo development and cell allocation in two developmental stages of day 7 blastocysts

Maturation of oocytes and the subsequent outcome of the in vitro production (IVP) are affected by the composition of in vitro maturation (IVM) medium. To determine the use of serum interfering with effects of single molecules, we aimed at developing simplified IVM medium. The experimental IVM media were: (1) M199-medium supplemented with hormones and serum (control), (2) as 1 but serum was substituted with fatty acid-free serum albumin (FAFBSA) and (3) M199-medium without hormonal and serum supplementation (M199). The quality of embryos was assessed on day 7 by morphology and cryotolerance, as well as by Terminal deoxynucleotidyl Transferase Biotin-dUTP Nick End Labeling (TUNEL) and differential staining. Results showed that the nuclear maturation was suppressed in M199 group alone. Embryo cleavage and development rates, and the proportion of quality 1 blastocysts were lower in the FAFBSA and M199 groups compared to the control. Differences in the cell allocation of fresh embryos were observed at the blastocyst stage, but not at the expanded blastocyst stage. The control group blastocysts had larger number of cells allocated to the inner cell mass (ICM), and the FAFBSA group blastocysts larger apoptotic cell proportion compared to the blastocysts derived from other groups. After cryopreservation, the reduction of ICM proportion and increase of apoptotic cell proportion of embryos were equal between the experimental groups. In conclusion, exclusion of serum from the IVM media reduces embryo development and may cause perturbations in blastocyst development. Differences in the cell allocation of blastocysts between IVM media may appear only when the developmental stages are taken into account.

Viljojen mykotoksiinit Suomessa

MMM:n johtama viljojen turvallisuustietojen seuranta vuosina 1999 – 2006 toteutti kansallisen viljastrategian päämääriä. Viljastrategiassa korostettiin viljantuotannon kannattavuuden ja kilpailukyvyn parantamista, laadun kehittämistä ja lisäarvon luontia laatuketjuun. Turvallisuustietoseuranta kohdistui viljojen hometoksiineihin, raskasmetalleihin ja torjunta-ainejäämiin. Pääasiassa seurantatutkimus keskittyi viljojen Fusarium -toksiineihin. Tutkimus toteutettiin Eviran, Pro Agrian ja MTT:n yhteistyönä. Turvallisuustietoseurannan keskeisiä tavoitteita oli hometoksiinipitoisuuksien seurannan lisäksi viljanäytteiden viljelytekniikka- ja viljelyolosuhdetietojen ja hometoksiinipitoisuuksien syy-seuraussuhteiden analysointi. Näytteiden taustatietoja kerättiin koko tutkimuksen ajan maalajeista, lajikkeista, typpilannoituksesta, siemenen laadusta, esikasveista, viljelykierrosta, kasvinsuojelutoimenpiteistä, kasvuajasta, korjuukosteudesta, kuivauksesta ja sadon määrästä. Turvallisuustietoseurannan tulosten perusteella kevätviljat olivat alttiimpia Fusarium -sienten tartunnalle ja toksiinien muodostumiselle. Syysviljojen hometoksiinipitoisuudet olivat koko seuranta-jakson hyvin alhaisia ja pääasiassa alle määritysrajojen. Kaikista tutkituista viljanäytteistä (991 kpl) vuosina 1999 – 2006 EU -raja-arvon ylittäviä pitoisuuksia DON:n osalta oli 18 kpl. Mikäli tarkastellaan ainoastaan kauranäytteiden DON -pitoisuuksia, raja-arvon 1750 µg/kg ylityksiä oli 11 kpl tutkituista 279 näytteestä. Kauranäytteistä lastenruoan raja-arvon 200 µg/kg alittavia näytteitä oli 164 kpl. Kaura oli viljoistamme selvästi herkin Fusarium -tartunnalle ja toksiinien muodostumiselle. Lisäksi rehuohralla ja kevätvehnällä havaittiin raja-arvon ylityksiä. Hometoksiinien hallinnassa tärkeintä oli siemenen kunnostus ja peittaus, viljelykierto, sadonkorjuun ajoitus ja viljan kuivaus. Myöhäinen lajike lisäsi toksiiniriskiä, koska kasvukauden venyminen pitkälle loppukesään lisää epävarmuutta sadonkorjuuajan säästä. Lakoontuneessa kasvustossa riski hometoksiinien muodostumiseen kasvoi. Viljan huolellinen lämminilmakuivaus alle 14 %:iin myös hyvinä vuosina oli parhaita keinoja hallita hometoksiiniriski. Turvallisuustietoseurannan tuloksia hyödynnettiin monin eri tavoin viljaraaka-aineen turvallisuutta arvioitaessa, viljan hyvät tuotanto- ja varastointitavat ja punahomeet viljassa -oppaassa, yritysten omavalvonnassa, neuvonnassa, valvonnassa, riskin arvioinnissa ja uusien tutkimuskohteiden valin-nassa. Fusarium -toksiinien seurannasta muodostui aikavälillä 1999 – 2006 vilja-alan toimijoiden yhteinen hanke, joka jatkuu edelleen ja kehittyy asiakkaiden tarpeiden mukaan.

297 A CASE REPORT: THE OUTCOME OF IVP MAY BE RELATED TO THE BATCH OF TCM-199 IN IVM

Chemicals used in bovine IVP may be inhibitory to embryo development (see, e.g., Van Soom A et al. 1994 Theriogenology 41, 325). The present study continued earlier experiments to optimize serum-free IVM protocol for bovine oocytes (Räty M. 2004 Reprod. Fert. Dev. 16, 281). The embryo development rate was much lower in the new experiments than in our previous studies. Thorough testing indicated that the batch of TCM-199 medium used in maturation was the reason for the lower embryo development results. In total, 14,589 abattoir-derived bovine oocytes in 23 batches were matured for 24 h in TCM-199 with glutamax-I (GIBCO, Paisley, UK), 0.25 mM Na-pyruvate, 100 IU mL−1 penicillin, 100 μg mL−1 streptomycin, 10 μg mL−1 LH, 2 μg mL−1 FSH, and 1 μg mL−1 β-estradiol supplemented as follows: (1) 10% FBS (GIBCO, New Zealand); (2) 4 mg mL−1 fatty acid-free albumin (FAFBSA) (Sigma-Aldrich, Helsinki, Finland); (3) 4 mg mL−1 polyvinylpyrrolidone (PVP) (Sigma) + growth factors (GF; 100 ng mL−1 IGF-I + 100 ng mL−1 EGF); or (4) as (3) but without FSH, LH, and β-estradiol (PVPGFwoH). Fertilized oocytes were denuded and cultured in modified SOFaaci + 4 mg mL−1 FAFBSA in 5% O2. (Holm P. et al. 1999 Theriogenology 52, 683–700). Two TCM-199 batches were used in separate IVM runs, batch 1 (Lot#3075638; 10 runs) and batch 2 (Lot#3081334; 13 runs). The statistical analyses were based on generalized linear mixed models. The estimated probabilities for embryo cleavage and development are shown in Table 1. The use of TCM-199 batch 1 resulted in significantly lower embryo development rates than the use of TCM-199 batch 2 in every IVM group studied. PVP IVM groups were the most sensitive for the TCM-199 batch and resulted in reduced embryo cleavage as well as strikingly low Day 7 embryo development. Our results indicate that TCM-199 batch 1 disturbed embryo development. In defined IVM groups (PVP groups), the maturation inhibiting role of TCM-199 batch 1 was seen already at the cleavage stage. It is possible that FBS and FAFBSA may have protected the oocytes to some extent against inhibitory effects of TCM-199. There is evidence for BSA acting as a chelating agent (see, e.g., Flood L.P. and Shirley B. 1991 Mol. Reprod. Dev. 30, 226–231). Table 1. Estimated probability for embryo cleavage at 38–42 hpi and Day 7 embryo development after IVM in two different batches of TCM-199

286 THE EFFECT OF IN VITRO MATURATION MEDIUM ON CRYOSURVIVAL, CELL NUMBERS AND APOPTOTIC INDEXES OF BOVINE EMBRYOS

The success of in vitro maturation (IVM) has a significant impact on the oocytes ability to develop to blastocyst stage. The quality of the produced blastocysts can be evaluated using staining techniques. The aims of this study were (a) to compare the effect of different IVM media on embryo production rates, and (b) to utilize differential (DF) and TUNEL staining to evaluate the quality and cryosurvival of the produced blastocysts. Abattoir-derived oocytes were randomly divided into the IVM groups: (1) M199 IVM (n = 2305): TCM-199 with glutamax-I (GIBCO, Paisley, UK), 0.25 mM Na-pyruvate, 100 IU mL−1 penicillin, and 100 μg mL−1 streptomycin; (2) FBS IVM (n = 2484): M199 IVM medium with hormones (10 μg mL−1 LH, 2 μg mL−1 FSH, and 100 μg mL−1 β-estradiol), and 10% FBS (GIBCO, New Zealand); and (3) FAFBSA IVM (n = 2411): as group (2), but FBS was replaced with 4 mg mL−1 fatty acid free albumin. Fertilized oocytes were denuded and cultured in modified SOFaaci + 4 mg mL−1 FAFBSA in 5% O2 (Holm P et al. 1999 Theriogenology 52, 683–700). Fresh, Grade I Day 7 blastocysts were stained with TUNEL (n = 114) or with DF (n = 149). In addition, 184 Grade I Day 7 blastocysts were frozen in AG Freeze (AB Technology, Pullman, WA, USA), thawed, and cultured for 24 h. The re-expanded embryos were stained with TUNEL (n = 96) or with DF (n = 88). Modified TUNEL protocol (Upstate, Lake Placid, NY, USA; Makarevich A and Markkula M 2002 Biol. Reprod. 66, 386–392) and DF staining protocol (Thouas G.A. et al. 2001 Reprod Biomed Online 3, 25–29) were used. The results of embryo cleavage and D7 embryo development are based on logistic regression models, and the results of proportion of ICM and apoptotic index on general linear mixed models. After FBS IVM, 83.6% of the fertilized oocytes were estimated to cleave and 25.5% to develop to the blastocyst stage by Day 7. The estimations for embryo cleavage and Day 7 development rates were significantly lower in FAFBSA IVM and M199 IVM groups (P < 0.0001): 74.0% and 15.0% for the FAFBSA, and 76.1% and 8.8% for the M199, respectively. The re-expansion rates (%) after thawing were 86.5, 90.6, and 73.3 for the FBS, FAFBSA, and M199 IVM groups, respectively. Freezing reduced the ICM proportions and elevated the apoptotic indexes (P < 0.001). The rate of ICM reduction after freezing was not influenced by the IVM medium. There was a significant interaction between the apoptotic index and the IVM group (P = 0.04). The increase of the apoptotic index was smallest in FAFBSA IVM and greatest in M199 IVM. The results indicate that exclusion of serum from IVM medium results in lower embryo cleavage and development rates. Freezing reduced ICM and increased apoptotic index of Day 7 embryos in every IVM group studied. FAFBSA IVM seemed to produce embryos of better quality as evidenced by the smallest increase in the apoptotic index after freezing.

Decreased nitrogen rates and irrigation effect on celery yield and internal quality

The effect of decreased nitrogen rates (90, 60 and 30 kg N/ha) with and without irrigation on celery yield quantity and internal quality were studied in field experiments in 1993 and 1994. The decreased nitrogen rates reduced yields in both years. In the dry and warm conditions of 1994 nitrogen x irrigation interaction was clearly observed; irrigation increased yield more at higher nitrogen rates than at lower nitrogen rates. In the rainy conditions of 1993 irrigation did not effect the yield level. On the other hand, in both years, decreased nitrogen rates increased dry matter, vitamin C and dietary fiber contents, and nitrogen had a minor effect on total sugar content. In 1994 alpha- and beta carotene and thiamin were also analyzed but nitrogen had no effect on them. Irrigation increased dry matter and total sugar contents at the two lowest nitrogen rates in 1994, but decreased vitamin C contents in both years. There was also slight evidence that irrigation might decrease alpha- and beta-carotene and thiamin contents.

The role of the large intestine in post-ruminal digestion of feeds as measured by the mobile-bag method in cattle

To study the importance of site of recovery and other factors related to mobile-bag (MB) digestion values, two consecutive experiments in which diets were applied in a 3 x 3 Latin square design, were carried out with cannulated growing heifers. In Expt 1, several types of experimental feed were exposed to intestinal digestion in mobile bags made of two cloth types and filled with intact or rumen-undegradable (RUD) feed material to be recovered either from the ileum (IB) or faeces (FB). In Expt 2, mean retention time (MRT) of Yb-labelled digesta particles within the intestine and in vivo digestibility of diets were measured. With vegetable concentrates, FB resulted generally in slight overestimation of small-intestinal dry matter and N digestion, while with meat-and-bone meal no difference between FB and IB was found. The respective N digestibility of RUD late-cut silage was clearly underestimated as measured from FB. The disappearance of neutral-detergent fibre (NDF) of all feeds under test was higher from FB than from IB. It was not possible to isolate the influence of the large intestine on the MB values by changing bag cloth type. Irrespective of the longer retention time of bags and longer MRT of Yb in the intestine on a low as compared with a high level of feeding, only NDF disappearance of feeds increased due to lower feeding level. Altering the diet type to increase large-intestinal fermentation, as indicated in vivo, usually had no effect on the MB values. It is concluded that the site of collection of bags does not practically affect small-intestinal digestion values of feed N, unless the feed is rich in fibre.