DOC and DON from grass-clover - results from a field experiment

The C and N dynamics in perennial grass-clover mixtures are not fully understood although such mixtures dominate temperate grassland. The co-existence of clover and grass involves both competition for and transfer of nutrients between the species. The nutrients that are competed for and transferred may originate from leaky root systems, from a rapid turnover of the fine root systems, or from degradation of more stabile organic material. The aim of the present study was to investigate the origin of dissolved organic C and N in perennial grass-clover mixtures. In an existing grass-clover ley, field mezotrons (cylinders with a diameter 30 cm) were installed in the spring of 2003 to depths of 20, 40 and 60 cm. Suction cups was installed beneath the mezotrons in order to sample the soil solution during the growth season. In late June 2004 cross-labelling of clover and grass populations in the mezotrons was done by leaf labelling (5 days) of either grass or clover using 15N- and 14C-labelled urea. During the following 3 months the percolating soil solution was sampled either after heavy rain or after irrigation of the mezotrons and the content 15N- and 14C-labelled compounds were determined. Leaf material was harvested at tree times during the growth season and at the end of the growth season the mezotrons was excavated and the distribution of 15N and 14C in the plants and soil determined. 14C was detected in the percolating soil solution imediately after leaf-labelling was initiated, with the highest amounts occuring from labelled grass. The peak of 14C reached the depths of 20 and 40 cm between 3-10 and 5-15 days respectively after labelling was initiated while no 14C was detected beneath the 60 cm mezotrons. The majority of 14C in soil solution was identified to be 14CO2 originating either from root respiration or from biomass respiration of 14C-labelled root parts or root exudates. The transfer of 14C was higher from grass to clover than vice versa. This transfer of 14C properly occurs as 14CO2 exchange between the leaves or in the root zone. Transfer of 15N was highest from clover to grass, while the transfer from grass to clover was negligible. These observations confirm previous investigations of 15N transfer between grass and clover. No clear connection was found between the transfer of 14C and 15N. After excavation of the mezotrons 14C was found in higher amounts and at larger depths in the soil for grass compared to clover. The results from this experiment point to that in a grass-clover ley carbon would primarily originate from grass and nitrogen would come from clover. The depths at which 14CO2 is found in the soil solution seem to be somewhat related to the depth of 14C-labelled root material meaning that the rooting profile of a crop influence the deposition of carbon and nitrogen in the soil matrix. These findings add significant new dimensions to our current understanding of processes governing the build up of soil fertility under grass-clover leys

N2-fixation and residual N effect of four legume species and four companion grass species

Inclusion of forage legumes in low-input forage mixtures improves herbage production and soil fertility through addition of nitrogen (N) from N2-fixation. The impact of different grass-legume mixtures on the N contribution of the forage mixture has rarely been investigated under comparable soil and climatic conditions. We conducted a field experiment on a sandy soil at two nitrogen levels with seven two-species forage mixtures: alfalfa, bird’s-foot trefoil, red clover, or white clover in mixture with perennial ryegrass, and white clover in mixture with meadow fescue, timothy, or hybrid ryegrass. We found high N2-fixation of more than 300 kg N ha-1 from both red clover and alfalfa even when the two mixtures received 300 kg total-N ha-1 in cattle slurry. The addition of cattle slurry N fertilizer lowered N2-fixation for white clover and red clover as expected, but for bird’s-foot trefoil and alfalfa no changes in the proportion of N derived from N2-fixation was observed. We conclude that the competition for available soil N from perennial ryegrass in mixture was an important factor for the proportion of N in alfalfa, white clover, and bird’s-foot trefoil obtained from N2-fixation. White clover had a high proportion of N derived from atmosphere for all companion grasses despite significant differences in white clover proportion. Although the perennial ryegrass-alfalfa mixture in the grass phase yielded more than twice the N from N2-fixation compared to white clover in the perennial ryegrass mixture, this did not in the following year lead to higher residual N effects of alfalfa. Both in terms of N yield in the grass phase and N yield in the subsequent spring barley red clover contributed most to the improvement of soil N fertility

Forage herbs improve mineral composition of grassland herbage

Provision of an adequate mineral supply in the diets of ruminants fed mainly on grassland herbage can present a challenge if mineral concentrations are suboptimal for animal nutrition. Forage herbs may be included in grassland seed mixtures to improve herbage mineral content, although there is limited information about mineral concentrations in forage herbs. To determine whether herbs have greater macro- and micromineral concentrations than forage legumes and grasses, we conducted a 2-year experiment on a loamy-sand site in Denmark sown with a multi-species mixture comprised of three functional groups (grasses, legumes and herbs). Herb species included chicory (Cichorium intybus L.), plantain (Plantago lanceolata L.), caraway (Carum carvi L.) and salad burnet (Sanguisorba minor L.). We also investigated the effect of slurry application on the macro- and micromineral concentration of grasses, legumes and herbs. In general, herbs had greater concentrations of the macrominerals P, Mg, K and S and the microminerals Zn and B than grasses and legumes. Slurry application indirectly decreased Ca, S, Cu and B concentrations of total herbage because of an increase in the proportion of mineral-poor grasses. Our study indicates that including herbs in forage mixtures is an effective way of increasing mineral concentrations in herbage

Crude Oil Non-Pusher Secondary Seal

LectureCrude oil pipeline pumps traditionally suffer from seal leakage due to the fretting or wearing of the dynamic O-ring. A new concept secondary seal has been developed to eliminate this fretting occurrence. All major seal suppliers have products designed specifically for the operational challenges of crude oil pipeline services, some more than others recognize the application difficulties and have design characteristics that belie these. However none are designs based on non-pusher secondary seal concepts. This paper will look at the design theory of a non-collapsible flexible sealing membrane, the subsequent successful development and testing of a non-pusher elastomer seal, and field deployment

GrainLegsGo: Friske bælgfrugter til human konsum

Baggrund: En mere bæredygtig og grønnere europæisk landbrugssektor kræver ændringer i vores kost fra kød til planteproteinkilder. En større produktion af bælgfrugter kan forbedre dyrkningssystemerne gennem øget jordfrugtbarhed, diversificerede afgrøder og reducerede klima- og miljøpåvirkninger. Alligevel er det danske økologiske areal, som er dyrket med bælgplanter, meget lavt, og kun en lille del heraf er til konsum for mennesker. Formål: GrainLegsGo vil øge dyrkningen af friske bælgfrugter til human konsum, samtidig med at det giver miljø- og klimafordele og fremmer cirkulær bioøkonomi. Projektet bringer nøgleinteressenter sammen, øger forbrugernes bevidsthed og fremmer dyrkningen af nye og traditionelle bælgfrugter til frisk høst. Ved at optimere dyrkningen af bælgplanter øger GrainLegsGo effektiviteten og produktiviteten i økologiske dyrkningssystemer, også takket være mere produktive efterafgrøder og færre tilfælde af skadedyr og sygdomme

Bælgplanters mange bidrag til klimakampen

Undersøgelser peger på, at efterafgrødeblandinger med bælgplanter øger kvælstof- og kulstoftilførslen til gavn for både jordfrugtbarheden og klimaet

Row spacing and catch crop establishment in organic arable systems: a way to increase biological N fixation

Increasing the row space of spring wheat from 12 to 24 cm, but maintaining the same seeding density, didn´t decrease its yield. On the other hand, it positively influenced the growth of the undersown catch crop, a mixture of red clover, white clover, rye grass and chicory

Nitrogen leaching: a crop rotation perspective on the effect of N surplus, field management and use of catch crops

Components of the field nitrogen (N) balance (input and surplus) are often used to predict nitrate leaching from agricultural lands. However, management factors, such as use of catch crops, greatly affect the actual loss and are a key to reduce N leaching. The present study is based on the 4th cycle of a long-term crop rotation experiment in Denmark, and it aims to quantify, from a crop rotation perspective, the influence on N leaching from N input and surplus or management factors. The experiment included three cropping systems (two organic and one conventional) with or without use of animal manure and catch crops. N leaching was calculated from measurements of nitrate in soil water sampled with ceramic suction cups installed at 1 m depth in all plots. At the rotation level, over a four years period, N leaching was positively related to N input and surplus. However, the overall effect of N input and surplus on N leaching was lower than the effect of use of catch crops. The response rates of N leaching to increasing N inputs and N surplus were about 0.08 and 0.19-0.25, respectively. Catch crops reduced N leaching by 23 kg N ha-1, irrespective of conventional and organic management system, with legume-based catch crops being as effective as non-legumes. Animal manure increased N leaching in one of the organic systems. The organic system with two years of green manure per rotation cycle was the one at highest risk of N leaching, especially from crops following green manure incorporation. Spring wheat and potatoes were the two crops with highest N leaching, and a stable low level of N leaching was only achieved above a crop-specific threshold in catch crop biomass

Developing a Simple and Rapid Test for Monitoring the Heat Evolution of Concrete Mixtures for Both Laboratory and Field Applications

Recently, activities and interest in monitoring the heat evolution of cement hydration in concrete have increased. This is because the development of early-age concrete properties (such as workability, setting time, strength gain, and thermal cracking resistance) is predominantly influenced by the kinetics of cement hydration. Various test methods are currently available for measuring heat of cement hydration; however, most existing methods require expensive equipment, complex testing procedures, and/or extensive time, thus making them unsuitable for field application. Although ASTM C 186 is used for determining the heat of hydration of cement, there is no standard test method for concrete. The overall object of this three-phase study is to identify, develop, and evaluate a standard test procedure for monitoring pavement concrete using a calorimetry technique. It is envisioned that the newly developed calorimetry test method will be able to verify appropriate concrete proportions, to identify potentially incompatible materials and conditions, and to predict concrete performance. The primary objective of Phase II (presented in this report) is to establish a standard test procedure as well as the methods for interpreting the calorimeter test results. The newly developed calorimeter test is completed more quickly than ASTM C 186, in approximately 24 hours. Among a number of uses, the test can be utilized as a quality control measure for prescreening concrete materials and a prediction tool for early-age cracking. The Phase II results demonstrate that the new calorimetry test method has a high potential for detecting concrete incompatibility problems, predicting fresh concrete properties (such as set time), and assessing hardened concrete performance characteristics (such as strength gain and thermal cracking)

Crude Oil Non-Pusher Secondary Seal

LectureCrude oil pipeline pumps traditionally suffer from seal leakage due to the fretting or wearing of the dynamic O-ring. A new concept secondary seal has been developed to eliminate this fretting occurrence. All major seal suppliers have products designed specifically for the operational challenges of crude oil pipeline services, some more than others recognize the application difficulties and have design characteristics that belie these. However none are designs based on non-pusher secondary seal concepts. This paper will look at the design theory of a non-collapsible flexible sealing membrane, the subsequent successful development and testing of a non-pusher elastomer seal, and field deployment