Dirk Reheul

Farm Compost Application: Effects on Crop Performance

Compost application can contribute to agricultural sustainability. Municipal solid waste compost has been the subject of most of the research done so far. Farm compost (FC) has a different composition. It is made of varying ingredients available on the farm, e.g., wood chips and bark, manure, straw, crop residues and surplus grass and soil. Information is currently lacking on the agronomic value and environmental impact of FC. Therefore, a long-term field experiment was established to quantify the effect of FC application on crop performance and soil quality in a crop rotation of potatoes, fodder beet, forage maize and Brussels sprouts. This paper presents the results of the first four years of the ongoing field trial. In the fourth year of the experiment, the annual FC amendment resulted in a significant increase in dry matter yield for all four crops. Our results suggested that the positive effect of continual FC application was based on a combination of a slow release of nitrogen and providing better growing opportunities to the crops. Results on the effect of FC on the residual nitrate content in the soil, disease suppression and DM content of the crops are not yet decisive.

Chilling tolerance and early vigour-related characteristics evaluated in two Miscanthus genotypes

A long growing season, mediated by the ability to grow at low temperatures early in the season, can result in higher yields in biomass of crop Miscanthus. In this paper, the chilling tolerance of two highly productive Miscanthus genotypes, the widely planted Miscanthus × giganteus and the Miscanthus sinensis genotype ‘Goliath’, was studied. Measurements in the field as well as under controlled conditions were combined with the main purpose to create basic comparison tools in order to investigate chilling tolerance in Miscanthus in relation to its field performance. Under field conditions, M. × giganteus was higher yielding and had a faster growth rate early in the growing season. Correspondingly, M. × giganteus displayed a less drastic reduction of the leaf elongation rate and of net photosynthesis under continuous chilling stress conditions in the growth chamber. This was accompanied by higher photochemical quenching and lower nonphotochemical quenching in M. × giganteus than that in M. sinensis ‘Goliath’ when exposed to chilling temperatures. No evidence of impaired stomatal conductance or increased use of alternative electron sinks was observed under chilling stress. Soluble sugar content markedly increased in both genotypes when grown at 12°C compared to 20°C. The concentration of raffinose showed the largest relative increase at 12°C, possibly serving as a protection against chilling stress. Overall, both genotypes showed high chilling tolerance for C4 plants, but M. × giganteus performed better than M. sinensis ‘Goliath’. This was not due to its capacity to resume growth earlier in the season but rather due to a higher growth rate and higher photosynthetic efficiency at low temperatures.

In situ quantification of forage grass root biomass, distribution and diameter classes under two N fertilisation rates

Background & aimsRoots are of paramount importance in protecting grassland in numerous ecosystem services e.g. soil organic matter build-up. However, studies that quantified root biomass in grasslands predominantly focused on areas managed less intensively than the management that is common to most North-West European grassland-based farms. To fill this knowledge gap, we compared, root and stubble biomass, the distribution in the soil and root diameter classes of five common European forage grass species grown under intensive management.MethodsOn a 3xa0year old trial comparing yield of five cool season forage grass species at two N fertilization levels (190xa0kgxa0Nxa0ha−1 yr−1 or 300xa0kgxa0Nxa0ha−1 yr−1) we sampled root and stubble biomass until a depth of 90xa0cm deep.ResultsTall fescue (Festuca arundinacea) displayed the highest root and stubble biomass and had the highest mean root diameters of all studied grass species. The total dry biomass below cutting height (stubbleu2009+u2009roots up to a depth of 90xa0cm below the soil surface) varied between 18 and 19 tonnes ha−1 for tall fescue and 10 and 11 tonnes ha−1 for Festulolium at 190xa0kgxa0Nxa0ha−1 yr−1 and 300xa0kgxa0Nxa0ha−1 yr−1, respectively.ConclusionsOur findings emphasize that in intensively managed grassland, root and stubble biomass under a 3xa0years old sward can be as high as 19xa0t DM ha−1. Owing to the high forage and root biomass of tall fescue, this species has a high potential in maintaining several ecosystem services.

Absorption, translocation and metabolism of metamitron in Chenopodium album

BACKGROUNDnIn recent years, common lambsquarters (Chenopodium album L.) populations from sugar beet fields in different European countries have responded as resistant to the as-triazinone metamitron. The populations have been found to have the same D1 point mutation as known for atrazine-resistant biotypes (Ser264 to Gly). However, pot experiments revealed that metamitron resistance is not as clear-cut as observed with triazine resistance in the past. The objectives of this study were to clarify the absorption, translocation and metabolic fate of metamitron in C. album.nnnRESULTSnRoot absorption and foliar absorption experiments showed minor differences in absorption, translocation and metabolism of metamitron between the susceptible and resistant C. album populations. A rapid metabolism in the C. album populations was observed when metamitron was absorbed by the roots. The primary products of metamitron metabolism were identified as deamino-metamitron and metamitron-N-glucoside. PABA, known to inhibit the deamination of metribuzin, did not alter the metabolism of metamitron, and nor did the cytochrome P450 inhibitor PBO. However, inhibition of metamitron metabolism in the presence of the cytochrome P450 inhibitor ABT was demonstrated.nnnCONCLUSIONnMetamitron metabolism in C. album may act as a basic tolerance mechanism, which can be important in circumstances favouring this degradation pathway.

A Review of Frost and Chilling Stress in Miscanthus and Its Importance to Biomass Yield

Miscanthus is a perennial grass used as a low input biomass crop. Yield limitations are caused mainly by abiotic stresses such as cold, drought, and salinity. This review summarizes the current knowledge of the cold tolerance of miscanthus. Miscanthus has a relatively high cold tolerance compared to related C4 crops such as maize, sorghum, or sugarcane. M. × giganteus, the most commonly planted clone, has a high chilling tolerance compared to most other miscanthus genotypes tested thus far. A small number of recently reported genotypes with an even higher cold tolerance allow for further breeding improvements. The high rates of photosynthesis at low temperatures of M. × giganteus are not an effect of special protective mechanisms but rather of increased production of photosynthetic enzymes. M. × giganteus is relatively susceptible to frost damage in its rhizomes as well as its aboveground parts. Developing improved miscanthus varieties with increased cold tolerance could result in earlier canopy formation and a longer growing season resulting in larger biomass accumulation over the year and higher yields. Increased cold tolerance would allow to expand the miscanthus growing area and to reduce the risk of winter mortality.

Differential sensitivity of locally naturalized Panicum species to HPPD- and ALS-inhibiting herbicides

Panicum schinzii (Transvaal millet), P. dichotomiflorum (Fall panicum) and P. capillare (Witchgrass) are alien panicoid grasses that have gradually spread and are now locally naturalized in corn fields in Belgium. One of the possible reasons for their expansion in corn fields might be a lower sensitivity to post-emergence herbicides acting against panicoid grasses, in particular those inhibiting 4-hydroxyphenyl pyruvate dioxygenase (HPPD) and acetolactate synthase (ALS). Dose-response pot experiments were conducted in the greenhouse to evaluate the effectiveness of five HP-PD-inhibiting herbicides (sulcotrione, mesotrione, isoxaflu-tole, topramezone, tembotrione) and two ALS-inhibiting herbicides (nicosulfuron, foramsulfuron) for controlling populations of P. schinzii, P. dichotomiflorum and P. capillare (all naturalized Belgian populations except for P. capillare). In another dose-response pot experiment, sensitivity of five local P. dichotomiflorum populations to HPPD-inhibitors and nicosulfuron was investigated. Finally, the influence of growth stage at time of herbicide application on efficacy of topramezone and nicosulfuron for Panicum control was evaluated. Large interspecific differences in sensitivity to HPPD-inhibiting herbicides were observed. Panicum schinzii was sensitive to tembotrione but moderately sensitive to to-pramezone and poorly sensitive to mesotrione and sulcotrione. However, P. dichotomiflorum was sensitive to mesotrione and topramezone but moderately sensitive to tembotrione. All Panicum species were sensitive to low doses of nic-osulfuron and foramsulfuron. Naturalized P. dichotomiflorum populations exhibited differential herbicide sensitivity profiles. All species tested showed a progressive decrease in sensitivity to topramezone and nicosulfuron with seedling age. A satisfactory post-emergence control of Panicum species in the field will require appropriate choice of herbicide and dose, as well as a more timely application (i.e. before weeds reach the four leaves stage).

Physiological basis of chilling tolerance and early-season growth in miscanthus

Background and AimsnThe high productivity of Miscanthus × giganteus has been at least partly ascribed to its high chilling tolerance compared with related C4 crops, allowing for a longer productive growing season in temperate climates. However, the chilling tolerance of M. × giganteus has been predominantly studied under controlled environmental conditions. The understanding of the underlying mechanisms contributing to chilling tolerance in the field and their variation in different miscanthus genotypes is largely unexplored.nnnMethodsnFive miscanthus genotypes with different sensitivities to chilling were grown in the field and scored for a comprehensive set of physiological traits throughout the spring season. Chlorophyll fluorescence was measured as an indication of photosynthesis, and leaf samples were analysed for biochemical traits related to photosynthetic activity (chlorophyll content and pyruvate, Pi dikinase activity), redox homeostasis (malondialdehyde, glutathione and ascorbate contents, and catalase activity) and water-soluble carbohydrate content.nnnKey ResultsnChilling-tolerant genotypes were characterized by higher levels of malondialdehyde, raffinose and sucrose, and higher catalase activity, while the chilling-sensitive genotypes were characterized by higher concentrations of glucose and fructose, and higher pyruvate, Pi dikinase activity later in the growing season. On the early sampling dates, the biochemical responses of M. × giganteus were similar to those of the chilling-tolerant genotypes, but later in the season they became more similar to those of the chilling-sensitive genotypes.nnnConclusionsnThe overall physiological response of chilling-tolerant genotypes was distinguishable from that of chilling-sensitive genotypes, while M. × giganteus was intermediate between the two. There appears to be a trade-off between high and efficient photosynthesis and chilling stress tolerance. Miscanthus × giganteus is able to overcome this trade-off and, while it is more similar to the chilling-sensitive genotypes in early spring, its photosynthetic capacity is similar to that of the chilling-tolerant genotypes later on.

The effect of maize silage type on the performances and methane emission of dairy cattle.

To examine whether type of maize silage is important for milk production performances, maize silage LG30224 (LG) was compared with Falkone (FA), the latter having a 4.0% points lower rumen NDF digestibility and 19xa0g/kg dry matter (DM) more starch. To bridge the lower energy content of FA, a third treatment was involved by adding maize meal (MM) in a ratio of 92/8 on DM (FA+MM). Maize and grass silage were fed adxa0libitum in a ratio of 65/35 on DM basis. Concentrates were supplemented individually to meet energy and protein requirements. The experiment was set up as a Latin square with three groups of nine Holstein cows during three periods of 3xa0weeks. In the last 2xa0weeks of each period, DM intake (DMI) and milk performances were measured. Each group included one cannulated cow to study effects on rumen fermentation. During the last 4xa0days of each period, two cows from each group were placed in gas exchange chambers to measure nutrient digestibility and methane production. Total DMI was higher (pxa0<xa00.05) for FA+MM (20.8xa0kg/day) than for FA (20.3xa0kg/day), while DMI for LG was intermediate (20.6xa0kg/day). Treatment did not affect milk production nor composition, whereas fat-protein-corrected milk was higher for LG (30.5xa0kg/day) and FA+MM (30.3xa0kg/day) than for FA (29.9xa0kg/day). The ration did not affect pH nor volatile fatty acid composition in the rumen. Further, total tract digestibility of OM, crude protein, NDF and starch did not differ among treatments. The ration with LG gave higher methane production per day and per kg NDF intake than both rations with FA, but the difference was not significant when expressed per kg DMI or FPCM. Thus, maize silage type is of little importance for milk production if energy and physical structure requirements are met.

Morpho-physiological responses to dehydration stress of perennial ryegrass and tall fescue genotypes

Worldwide drought stress is the most important restriction factor on food and fodder productivity. In this study, morpho-physiological adaptations to dehydration stress were investigated in two tall fescue (Festuca arundinacea Schreb.) genotypes (Fa13 and Fa19 with a high and low sheep grazing preference respectively) and Lolium perenne L. Drought stress as evaluated by decreasing stomatal conductance and chlorophyll content, chlorophyll fluorescence parameters and fructan concentration were first observed in L. perenne (16 days after the start of the drought stress). Furthermore, after 20 days of drought stress the activities of ascorbate peroxide (APX), catalase (CAT), and superoxide dismutase (SOD) were reduced in stressed plants indicating that the capacity to scavenge ROS diminished under severe stress though no differences between genotypes were observed. Osmotic adjustment by carbohydrates did also not differ between the genotypes. Proline, however, reached its highest level in drought-stressed L. perenne followed by Fa13 and Fa19 respectively. The studied species showed a similar degree in response in the traits assessed when plants were exposed to dehydration stress; however changes were first observed in L. perenne.

Harvest date does not influence variety ranking in Belgian forage maize variety trials

Silage maize variety testing systems usually evaluate new varieties within properly defined maturity groups; within a maturity group, all varieties are harvested on a single harvest date. In a small country like Belgium where growing conditions are similar across the maize growing areas, all tested silage maize varieties, comprising different maturity groups, are harvested on a single date. Under this testing system, only few varieties are harvested at the physiological stage where they theoretically show their optimal performance. In the current research, eight silage maize varieties were monitored from 25 to 40% whole-crop dry matter (DM) content at three locations in Belgium during the period 2007-2009. The optimal harvest date was calculated as the date where whole-crop DM yield, ear DM yield and organic matter digestibility were maximal. The variety rank at the optimal harvest date was compared with the variety rank at any studied single harvest date. Harvest dates where the variety rank was not statistically different to the rank at the optimal harvest date were pooled in a harvest window. Based on the current data, the harvest window comprised a flexible harvest period of about 14 days. It was therefore concluded that applying a single harvest date is scientifically justified for the ranking of silage maize varieties in Belgium, when the whole-crop DM content is between 28.1 and 40.6% with a maximum difference of 7.2% between all compared varieties.