Availability of N to plants from legume and fertilizer sources: which is greater?

Non-Peer ReviewedOne benefit often cited for legumes crops is that they contribute N to subsequent crops, but the magnitude of this effect has been difficult to quantify. A study was conducted to compare how much and when N from fertilizer and residue sources was taken up by wheat Wheat straw (W), lentil straw (L), and lentil green manure (G), unenriched or enriched in 15N, were both surface placed and incorporated into microplots (10 x 40 cm) in the field in the fall of 1988. In the spring of 1989 wheat was planted in all microplots, and unenriched and enriched fertilizer N was added to microplots containing enriched and unenriched plant residues, respectively. Microplots were destructively sampled at planting and at 6, 10 and 13 weeks after planting. Approximately 29 % of added fertilizer was recovered in wheat tops by 6 weeks after planting in all treatments except incorporated W, where immobilization reduced this value to 19 %. Maximum recoveries of fertilizer 15N were 34 % by the final sampling date. The proportion of residue 15N recovered in wheat tops at the final sampling dates was 19 and 11 % from incorporated and surface-placed G, respectively, and 5.4 and 5.3 % from L and W, respectively. Surface placement of residues reduced immobilization of fertilizer N but increased losses of residue N. Comparisons of N availability based on recovery of 15N may be misleading because 15N recovery does not account for changes in mineralization of native N, which is likely to be affected unequally by the addition of different N sources

Comparison of available soil moisture and nitrogen following wheat and lentil

Non-Peer ReviewedLentil is generally grown in rotation with cereals, and may benefit the succeeding crop by using less moisture or by increasing the amount of available N. Soil moisture and N depletion was measured for lentil and wheat at five sites in 1985, three sites in 1987 and one in 1988. Lentil depleted soil moisture and mineral N to a similar extent as wheat at most sites. Exceptions occurred due to differences between lentil and wheat in their response to rainfall distribution or in their effectiveness at exploiting moisture and nitrate at deeper soil layers. Lentil residues contained more N than wheat residues, but this did not represent a net gain in N because as much N was removed with the seed as was fixed. Lentil residues had a higher and more variable N concentration than wheat Thus, net N mineralization will on average be higher following lentil than following wheat, but the magnitude of these differences will be variable

Quantum storage on subradiant states in an extended atomic ensemble

A scheme for coherent manipulation of collective atomic states is developed such that total subradiant states, in which spontaneous emission is suppressed into all directions due to destructive interference between neighbor atoms, can be created in an extended atomic ensemble. The optimal conditions for creation of such states and suitability of them for quantum storage are discussed. It is shown that in order to achieve the maximum signal-to-noise ratio the shape of a light pulse to be stored and reconstructed using a homogeneously broadened absorbtion line of an atomic system should be a time-reversed regular part of the response function of the system. In the limit of high optical density, such pulses allow one to prepare collective subradiant atomic states with near flat spatial distribution of the atomic excitation in the medium.Comment: V2: considerably revised (title, text). V3: minor changes - final version as published in PR

Nitrogen, phosphorus, and rhizobial strain responses of lentil

Non-Peer ReviewedThree field experiments were set out in 1987 to test the effect of nitrogen fertilizer, phosphorus fertilizer, and rhizobial strain on lentil yields and N2 fixation. The following treatments were laid out in a split-split-plot design: main plot treatments of uninoculated, Nitragin 'C' inoculated, and strain 99A1 inoculated lentil; sub-plot treatments of 0 and 30 kg P/ha, and sub-sub plot treatments of 0, 10, 20, 40, or 80 kg N/ha 15N-enriched fertilizer was applied to a 1.05 m2 microplot in each plot Barley was used as the non-N2-fixing reference crop. At all sites lentil inoculated with strain 99A1 had the greatest total dry matter yield, grain yield and N2 fixed. Uninoculated lentil had a strong N response at all sites, 'C' inoculated lentil had a starter N response at Kindersley and 99A1 inoculated lentil had no N response at all. P responses were only observed at Foam Lake. Lentil receiving low amounts of N fertilizer obtained between 60 and 75 % of their N from the atmosphere at all sites. A good agreement was observed in estimating percent N derived from N2 using the 15N isotope dilution, A-value, or classical N-difference methods. The amount of fixed-N in the seed ranged from 4 kg ha-1 under drought stressed conditions at Kindersley to 60 kg ha-1 under much better growing conditions at Foam Lake

Growth and water use of irrigated and dryland lentils and wheat

Non-Peer ReviewedLentils are becoming an increasingly more important crop in Saskatchewan with over 230,000 ha planted in 1987. A large part of this acreage was in the Brown Soil Zone. To date lentil water relations and adaptation to water deficits are largely undescribed. This study was initiated to determine the drought tolerance characteristics of lentils and to compare them to those of wheat growing under the same weather conditions. Dryland lentils exhibited considerable drought tolerance with large changes in osmotic potential in response to increasing soil water deficits. Despite maintaining high levels of turgor, values of stomatal conductance were very low. This behaviour enabled leaves to maintain high relative water contents and survive an extensive dry period. In contrast wheat displayed little drought tolerance. Consequently throughout the growing season the rates of dry land to irrigated above-ground dry matter was consistently higher for lentils than for wheat and at final harvest was 0. 71 and 0.41 for the two crops, respectively. Wheat and lentils had similar water use efficiencies, but lentils used more water because of their greater dry matter production. Very high dry matter production in irrigated lentils did not translocate into high grain yields

Path Integrals in Polar Field Variables in QFT

We show how to transform a $d$-dimensional Euclidean path integral in terms of two (Cartesian) fields to a path integral in terms of polar field variables. First we present a conjecture that states how this transformation should be done. Then we show that this conjecture is correct in the case of two toy models. Finally the conjecture will be proven for a general QFT model with two fields

NMR Simulation of an Eight-State Quantum System

The propagation of excitation along a one-dimensional chain of atoms is simulated by means of NMR. The physical system used as an analog quantum computer is a nucleus of 133-Cs (spin 7/2) in a liquid crystalline matrix. The Hamiltonian of migration is simulated by using a special 7-frequency pulse, and the dynamics is monitored by following the transfer of population from one of the 8 spin energy levels to the other.Comment: 10 pages, 3 figure

Lateral phase separation in mixtures of lipids and cholesterol

In an effort to understand "rafts" in biological membranes, we propose phenomenological models for saturated and unsaturated lipid mixtures, and lipid-cholesterol mixtures. We consider simple couplings between the local composition and internal membrane structure, and their influence on transitions between liquid and gel membrane phases. Assuming that the gel transition temperature of the saturated lipid is shifted by the presence of the unsaturated lipid, and that cholesterol acts as an external field on the chain melting transition, a variety of phase diagrams are obtained. The phase diagrams for binary mixtures of saturated/unsaturated lipids and lipid/cholesterol are in semi-quantitative agreement with the experiments. Our results also apply to regions in the ternary phase diagram of lipid/lipid/cholesterol systems

Simulation and Analysis of the Hybrid Operating Mode in ITER

The hybrid operating mode in ITER is examined with 0D systems analysis, 1.5D discharge scenario simulations using TSC and TRANSP, and the ideal MHD stability is discussed. The hybrid mode has the potential to provide very long pulses and significant neutron fluence if the physics regime can be produced in ITER. This paper reports progress in establishing the physics basis and engineering limitation for the hybrid mode in ITER