Crop yield, nitrogen uptake and nitrate-nitrogen accumulation in soil as affected by 23 annual applications of fertilizer and manure in the rainfed region of Northwestern China

Application of chemical fertilizers and farmyard manure affects crop productivity and improves nutrient cycling within soil–plant systems, but the magnitude varies with soil-climatic conditions. A long-term (1982–2004) field experiment was conducted to investigate the effects of nitrogen (N), phosphorus (P), and potassium (K) fertilizers and farmyard swine manure (M) on seed and straw yield, protein concentration, and N uptake in the seed and straw of 19-year winter wheat (Triticum aestivum L.) and four-year oilseed (three-year canola, Brassica napus L. in 1987, 2000 and 2003; one-year flax, Linum usitatisimum L. in 1991), accumulation of nitrate-N (NO₃-N) in the soil profile (0–210 cm), and N balance sheet on a Huangmian soil (calcaric cambisols, FAO) near Tianshui, Gansu, China. The two main plot treatments were without and with farmyard swine manure (M); sub-plot treatments were control (Ck), N, NP, and NPK.␣The average seed yield decreased in the order MNPK ≥ MNP > MN ≥ NPK ≥ NP > M > N > Ck. The average effect of manure and fertilizers on seed yield was in the order M > N > P > K. The seed yield increase was 20.5% for M, 17.8% for N, 14.2% for P, and 2.9 % for K treatment. Seed yield response to fertilizers was much greater for N and P than for K, and it was much greater for no manure than for manure treatment. The response of straw yield to fertilization treatments was usually similar to that of seed yield. The N fertilizer and manure significantly increased protein concentration and N uptake plant. From the standpoint of increasing crop yield and seed quality, MNPK was the best fertilization strategy. Annual applications of N fertilizer and manure for 23 successive years had a marked effect on NO₃-N accumulation in the 0–210 cm soil profile. Accumulation of NO₃-N in the deeper soil layers with application of N fertilizer and manure is regarded as a potential danger, because of pollution of the soil environment and of groundwater. Application of N fertilizer in combination with P and/or K fertilizers reduced residual soil NO₃-N significantly compared with N fertilizer alone in both no manure and manure plots. The findings suggest that integrated and balanced application of N, P, and K fertilizers and␣manure at proper rates is important for protecting soil and groundwater from potential NO₃-N pollution and for maintaining high crop productivity in the rainfed region of Northwestern China.     

Biomass estimation of mixed forest landscape using a Fourier transform texture-based approach on very-high-resolution optical satellite imagery

Assessment of forest structure parameters via remote-sensing data offers the opportunity to examine stand parameters and to detect degradation and forest dynamics, such as above-ground biomass (AGB), at the landscape scale. While much attention has focused on spectrum-based and radar backscatter approaches for assessing forest biomass, texture-based approaches show strong promise. This work makes use of the novel Fourier transform textural ordination (FOTO) method, which involves the combination of 2D fast Fourier transform (FFT) and ordination through principal component analysis (PCA) for characterizing the structural and textural properties of vegetation. This technique presents the potential of Fourier transform approaches in estimating the different forest types, their stand structure, and biomass dynamics in the context of an oil palm–tropical forest landscape in Sabah, Malaysian Borneo. The method was applied to the recordings of very-high-resolution (VHR) Satellite Pour l’Observation de la Terre (SPOT) imagery of the study area. The technique proved useful in distinguishing between the forest types and developing individual biomass estimate models for various forest types. Results show that the FOTO method is able correctly to resolve high AGB values of various forest types. These findings are in agreement with the results based on ground measurements.     

Banding increases effectiveness of fertilizer P for alfalfa production

A field experiment was conducted from 1992 to 1996 on an existing alfalfa (Medicago sativa Leyss) stand located on a P-deficient Black Chernozem (Typic Boroll) soil at Ponoka, Alberta, to compare the effectiveness of broadcasting (spread over the soil surface) versus banding (1.5 cm wide band placed 5 cm deep and 15 cm apart, using a coulter-type disc drill) of annual and one-time applications of P fertilizer on dry matter yield (DMY), P-use efficiency of applied P (PUE), protein yield (PY), recovery of fertilizer P (PR), net returns (NR) and non-renewable energy performance of alfalfa hay. There was a marked increase in DMY and PY from all the P application treatments in all the five years. Banding produced greater increase in DMY and PY than broadcasting, with both the annual (by 954 kg DMY ha^–1 and 205 kg PY ha^–1) and one-time application (by 742 kg DMY ha^–1 and 173 kg PY ha^–1) applications. The PUE (averaged across P rates and years) was greater with banding as compared to broadcasting by 58 kg DMY kg^–1 P ha^–1 for annual applications, and by 47 kg DMY kg^–1 P ha^–1 for one-time applications. In the same order, PR values were 16.0 and 12.1% greater with banding than broadcasting. Despite the higher costs of banding than broadcasting, net returns were significantly higher with banding in nearly all years. The differences between banding and broadcasting were generally greater at lower than at higher P rates. Based on the 5-year means, annual and one-time P applications produced similar increase in DMY, PY, PUE, PR and NR. In contrast, non-renewable energy inputs were higher for banding than broadcasting, but energy use efficiency was similar for both methods of application. In conclusion, method of P placement had the greatest effect on DMY, PY, PUE, PR, NR and energy performance, whereas annual and one-time applications showed similar results. The results suggest that alfalfa forage productivity and profitability can be improved by banding the P fertilizer with a coulter type disc in comparison to the conventional application method of broadcasting.     

In vitro cytotoxicity and teratogenicity of norethisterone and levonorgestrel released from hollow nylon monofilaments

We investigate the effect of the neuron characteristics on the behavior of a recurrent excitatory neural network model. First, we present the different types of dynamics obtained with simulations of a network of coupled excitatory spike-response neuron models placed under the influence of noise. Then, we derive a discrete map describing the dynamics of large fully connected networks. By studying the bifurcation structure of this map, we can determine for which ranges of the neuron model parameters the network will display collective oscillations or other types of dynamics.     

Effectiveness of fall- versus spring-applied urea on barley

Field experiments were conducted in north-central and central Alberta to determine the effect of pellet size and depth of placement on yield and N uptake of barley from fall- and spring-applied urea. The application rate was 56 kg N ha^–1. Fall incorporated commercial urea (0.01 g) gave 792 kg ha^–1 lower yield and 15 kg ha^–1 less N uptake than similarly applied commercial urea in spring on the average for the five experiments. The effectiveness of fall-applied N tended to be greater with large urea pellets (2.5 g), especially when they were placed 15 cm deep. Specifically, the relative yield efficiency of fallversus spring-applied N was 77% when the larger pellets were placed 4 cm deep and 95% when placed 15 cm deep. However, large pellets were less effective than commercial urea when both were applied in spring at sowing or two weeks before.     

Technical note Best connection scheme of collector modules of thermosyphon solar water heater operated at high temperatures

Large scale thermosyphon solar water heater for high temperature applications is simulated by the use of the Transient Simulation Program (TRNSYS). A daily hot water load of 1500 l/day and 2500 l/day at 80°C was assumed. The hot water is consumed daily from 08·00–17·00 h. A back-up electric auxiliary heater was added to the system in two schemes: first, located inside the storage tank with a thermostat; second, outside the tank connected to the heating system between the tank and the facilities. The collector modules were connected in five different schemes: first, all collectors were connected in series in one line, or collectors were connected in two, three, four or five parallel lines each consisting of many collectors. The results showed that the best connection is when the 20 collectors, comprising the system, are connected in two parallel lines each consisting of 10 collectors. It was found that the monthly and yearly useful energy from the system was higher when the auxiliary water heater was added to the system outside the storage tank.     

Long-term tillage,straw management and N fertilization effects on quantity and quality of organic C and N in a Black Chernozem soil

Soil, crop and fertilizer management practices may affect the amount and quality of organic C and N in soil. A long-term field experiment (growing barley, wheat, or canola) was conducted on a Black Chernozem (Albic Argicryoll) loam at Ellerslie, Alberta, Canada, to determine the influence of 19 (1980 to 1998) or 27 years (1980 to 2006) of tillage (zero tillage [ZT] and conventional tillage [CT]), straw management (straw removed [S_Rem]and straw retained [S_Ret]) and N fertilizer rate (0, 50 and 100 kg N ha⁻¹ in S_Ret and 0 kg N ha⁻¹ in S_Rem plots) on total organic C (TOC) and N (TON), and light fraction organic C (LFOC) and N (LFON) in the 0–7.5 and 7.5–15 cm or 0–5, 5–10 and 10–15 cm soil layers. The mass of TOC and TON in soil was usually higher in S_Ret than in S_Rem treatment (by 3.44 Mg C ha⁻¹ for TOC and 0.248 Mg N ha⁻¹ for TON after 27 years), but there was little effect of tillage and N fertilization on these parameters. The mass of LFOC and LFON in soil tended to increase with S_Ret (by 285 kg C ha⁻¹ for LFOC and 12.6 kg N ha⁻¹ for LFON with annual rate of 100 kg N ha⁻¹ for 27 years)_, increased with N fertilizer application (by 517 kg C ha⁻¹ for LFOC and 36.0 kg N ha⁻¹ for LFON after 27 years), but was usually higher under CT than ZT (by 451 kg C ha⁻¹ for LFOC and 25.3 kg N ha⁻¹ for LFON after 27 years). Correlations between soil organic C or N fractions were highly significant in most cases. Linear regressions between crop residue C input and soil organic C or N were significant in most cases. The effects of tillage, straw management and N fertilizer on soil were more pronounced for LFOC and LFON than TOC and TON, and also in the surface layers than in the deeper layers. Tillage and straw management had little or no effect on C:N ratios, but the C:N ratios in light organic fractions significantly decreased with increasing N rate (from 20.06 at zero-N to 18.91 at 100 kg N ha⁻¹). Compared to the 1979 results, in treatments that did not receive N fertilizer (CTS_Rem0, CTS_Ret0, ZTS_Rem0 and ZTS_Ret0), CTS_Rem0 resulted in a net decrease in TOC concentration (by 1.9 g C kg⁻¹) in the 0–15 cm soil layer in 2007 (after 27 years), with little or no change in the CTS_Ret0 and ZTS_Rem0 treatments, while there was a net increase in TOC concentration (by 1.2 g C kg⁻¹) in the ZTS_Ret0 treatment. Straw retention and N fertilizer application at 50 and 100 kg N ha⁻¹ rates showed a net positive effect on TOC concentration under both ZT (ZTS_Ret50 by 2.3 g C kg⁻¹ and ZTS_Ret100 by 3.1 g C kg⁻¹) and CT (CTS_Ret50 by 3.5 g C kg⁻¹ and CTS_Ret100 by 1.6 g C kg⁻¹) treatments in 2007 compared to 1979 data. In conclusion, the findings suggest that retention of straw, application of N fertilizer and elimination of tillage would improve soil quality, and this might increase the potential for N supplying power of the soil and sustainability of crop productivity.     

Potential for nitrate—N loss in central Alberta soils

Incubation experiments were conducted to determine the influence of soil type, soil depth and tillage-straw treatment on the capacity for NO₃-N loss under anaerobic incubation. In Experiment 1 with 14 cultivated surface soil samples, there were substantial NO₃-N losses in all soils regardless of the total organic carbon content. The total organic carbon content of these soils ranged from 21 to 55 g C kg^–1. Experiment 2 showed that the rate of NO₃-N loss decreased with depth of soil, but when glucose was added the rate of NO₃-N loss increased markedly and all of the added NO₃-N disappeared within less than a week. In Experiment 3, the soil under zero tillage where straw was retained gave slightly higher rate of NO₃-N loss than the soil from conventional tillage treatment. (Scientific Paper No. 628)     

On the method of extraction of lumped parameters for the radiation impedance of complex radiator geometries

This work addresses the problem of finding expressions for the radiation impedance of a circular plate with cuts (holes + slits) and mounted in an infinite baffle. Due to the nontrivial nature of the structural geometry and the boundary conditions, analytical solution of the required Rayleigh integral is difficult for this case. The analysis in this case is carried out numerically using COMSOL Multiphysics. The air on top in contact with the vibrating plate, loads the plate with additional mass and also dissipates away energy depending on the frequency of vibration. The numerical solution obtained using FEA needs to be converted into suitable frequency based expressions. We use curve fitting to relate these radiation impedance values to an already reported equivalent circuit (for modeling the radiation impedance) in the literature. The detailed method of lumped parameter extraction, as well as the method of reduction of the circuit to its high and low frequency counterparts, is reported in this paper. The method described here is a generic one and can be used for any kind of geometry.