Search

Soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) are essential nutrients for plant growth. Thus, soil amendments that increase the amounts of these nutrients can improve crop yield in poor growing soils such as Red soils in subtropical China, which were classified as Plinthosols in the WRB (World Reference Base for Soil Resources). It is unknown whether any of the three nutrients are more influential than the others on crop yield. A 30-year-long field experiment was established in 1986 to investigate the response of grain yield to changes in SOC, TN and TP levels, identified by regression equations, due to various fertilizer treatments applied to corn crops grown in red soil. Corn yields varied significantly under four different fertilizer treatments. For most of the experimental years, the two fertilizer treatments of application of manure combined with inorganic nitrogen, phosphorus, and potassium (NPKM) and a higher rate of NPK (HNPK) fertilizer produced significantly higher yields than the control (no addition of fertilizer, CK) by 441–548 and 380–703%, respectively. Differences between yields increased over time, particularly between NPKM and CK treatments. The long-term application of NPKM increased SOC, TN and TP contents more so than the other treatments and contents were greater than those in the CK by 48.6–57.1, 26.4–37 and 81.6–142%, respectively. There were no significant differences between the treatments with the low and high rates of NPK (LNPK and HNPK). Additional results showed that NPKM raised the C : N ratio and lowered the C : P ratio. The relationships between SOC, TN, TP and grain yield were best represented by the Michaelis–Menten equation rather than the simple linear equation. Moreover, the equations estimated different maximum yields of corn; yields estimated by SOC and TP were higher than the yield estimated by TN. Furthermore, The estimated maximum yield that could be attained is at a C : N ratio of 10.22 in red soil. Therefore, SOC and TP are likely the more important nutrients to consider altering in soil management of red soil.

Soil enzyme activity and microorganism community can be changed through different long-term fertilization patterns. However, the effect of different fertilization practices on soil microorganisms might differ among crop systems. The objective of the study was to reveal the change of soil enzyme activity and soil microorganism community in different fertilizations both in upland and paddy soils. Therefore, based on long-term fertilization experiments in upland soil started in 1986 and adjacent paddy soil experiment commenced in 1981, with both consisting of 4 treatments: Control (no fertilization), N (only nitrogen fertilizer), NPK (nitrogen, phosphate and potassium fertilizers) and NPKM (nitrogen, phosphate and potassium fertilizers plus organic manure), grain yield, soil fertility, activities of soil urease, catalase, acid phosphatase, microorganism community (the number of bacteria, fungus and actinomycete) were analyzed. The result showed that: the highest grain yield was attained under the application of chemical fertilizers plus manure, as compared with Control, NPKM significantly increased the grain yield by 908.63% in corn and 118.80% in rice (p

It may be good to estimate rice yield based on root bleeding snap weight (BSW) and leaf soil plant analysis development (SPAD) at grain filling stages in southeast China. There were seven treatments: (N-butyl) thiophosphorictriamide (NBPT) applied at rates of 0.00, 0.50, 0.75, 1.00, 1.25, 1.50% with urea @ 135 kg N ha -1 and CK (no NBPT or urea). All treatments received 75 kg P2O5 ha -1 (superphosphate, P2O5 12%) and 150 kg K2O ha -1 (potassium sulfate, K2O 60%), and then all fertilizer and inhibitor were applied once as base fertilizer. At grain filling stage, both of early and late rice, root BSW and leaf SPAD readings were obtained and grain yield determined at harvesting. In addition, the relationship between BSW, SPAD and grain yield was established. The results showed that the grain yield of rice, root BSW and leaf SPAD were increased significantly in application of NBPT with urea. Compared with 0% NBPT, grain yield, BSW and SPAD in 1.00% NBPT were improved by11.9-33.0%, 7.1-74.3% and 4.6-31.7% in early rice; and increased by 8.4-33.0%, 7.9-75.0% and 4.4-19.5% in late rice. However, these decreased when NBPT was less or more than 1.00%. On the other hand, the relationship between BSW, SPAD at grain filling stage and grain yield could be fitted by two-variable linear equation (p

The growth of ratoon rice (Oryza sativa L.) is affected by growth of main rice, so it could be evaluated by determining growing condition of main rice. Objective of the study was to find regression model for predicting ratoon rice growth rhythm through establishing the quantitative relationship between growth rhythm in ratoon rice and normalized difference vegetation index (NDVI) after heading of main rice. NDVI at key growth stages of main rice was measured using active spectrometry for 12 varieties in 2008 and for 23 varieties in 2009, and compared the physiological indexes of main and ratoon rice. There was an exponential correlation (P < 0.05) between the NDVI after heading of the main rice and biomass, N concentration of green leaves and stems or leaf area index (LAI) after heading of the ratoon rice for all the 12 varieties in 2008. The regression models from the rice variety experiment in 2008 were used to calculate predicted values with NDVI after heading of main rice in 2009. The results showed that the predicted values of biomass, N uptake, and LAI in ratoon rice were significantly different to measured values. However, there were exponential and significantly positive correlation (p < 0.05) between biomass and N uptake and LAI in ratoon rice and NDVI after heading of main rice in 2009. Therefore, it suggested that regression models were not perfect, and need to be improved adding more parameters about spectral characteristic of main and ratoon rice.

Traditional nursing operations have many disadvantages, such as low inefficiency, high risk, and large cost. Utilizing the existing simulation technology, a nursing virtual simulation laboratory characterized by informatization can be established. Nursing operations virtual simulation training system includes two major parts: simulation equipment, nursing virtual training and evaluation systems. It truly reproduces the first-line clinical nursing work scenarios, meets features of clinical practice teaching, that is, real, visual, and repeatable, greatly enhancing the practical ability of nursing students. It is an effective complement to the teaching methods with human as practical teaching object in nursing education, and has extensive development and application prospects.

The Quasi-orthogonal space-time block code ensure that data transfer at full speed. However, it will reduce the error performance. Based on it, this paper proposed a new quasi-orthogonal space-time block code using full rate of the four transmit antenna. And it proposed the decoding method based on maximum likelihood algorithm. A number of simulation results demonstrate that the proposed algorithm has better error performance than the typical Jafarkhani quasi-orthogonal space-time block code.

This paper analyzes the performance simulated of the space-time block coding orthogonal frequency division multiplexing (STBC-OFDM) system under different channel conditions after studying the STBC-OFDM system. From that it can be found that the BER performance of STBC-OFDM system is much better than the OFDM system without using Space-time coded.

In this paper, the steady-state behavior of L-band EDFA with an inline fiber grating laser is studied, and the physical process of signal amplification is simulated and analyzed in details. Good gain characteristics is achieved by incorporating a backward pump and optimizing the configuration of the Single-Stage L-EDFA. the power conversion efficiency is equal to 22%, the gain value is 25dB, the noise figure is less than 4.6dB, and the saturated output power is 21.5dBm. In addition, the gain flatness is less than ± 0.8dB, and the flatness of noise figure is less than ± 0.1dB within 35nm gain bandwidth.

This paper first studied a kind of vector control strategies based on the stator flux-oriented vector of the double-fed AC excited generator in the case of power grid voltage stable, establishes the simulation model based on Matlab/Simulink and simulation results are given. The results indicate that the stator flux-oriented vector control can achieve the regulation of active and reactive power for a double-fed induction generator (DFIG) independently. In order to improve DFIG uninterrupted running ability in the case of power grid voltage drop, on the basis of the DFIG precise mathematical model, this paper proposes an improved control mode, and carries on a simulation comparative analysis for the DFIG dynamic procedure under the condition of grid voltage drop before and after. The results show that the improved scheme can suppress the impact of the rotor current effectively and can improve the uninterrupted running ability of DFIG in the case of power grid voltage drop.