不同NPK配置对强筋小麦群体生物量与产量的效应研究

在关中川道灌区以强筋小麦陕253为材料,研究了不同NPK配置对其不同生育期生物产量、群体数量和产量的效应,结果表明提高施肥量可显著增加生物产量、群体数量及产量,处理平均值分别比常规处理增加11.9%~43.6%、4.1%~17.4%和8.3%,其最佳N、P、K配置依次为N135kg hm-2,P2O5和K2O各120kg hm-2、N135kg hm-2,P2O5225kghm-2,K2O120kg hm-2和N225kg hm-2,P2O5和K2O各120kg hm-2。在目前常规投肥水平下适度增加钾肥有利于生物产量的显著提高,增加磷肥和钾肥有利于群体数量的提高,增施氮钾肥有显著的增产效果。产量的最佳NPK配比较常规处理增产19.1%,其增加养分的平均产量4.44 kg kg-1,比各处理平均养分产量高1.6倍。     

河西灌漠土地区加工型甜椒配方施肥研究

采用3因素二次回归通用旋转组合设计,研究了氮肥、磷肥、钾肥对加工型甜椒产量的影响,得到了相应的回归数学模型。结果表明:三因素影响加工型甜椒产量的顺序为氮肥>钾肥>磷肥。各因素间存在交互作用。经过计算机模拟,得到加工型甜椒产量达到最高值时,其相对应N、P、K肥用量分别为N600kg hm-2、P2O597kg hm-2、K2O273kghm-2。对试验结果进行的验证表明,模型选优所得氮肥、磷肥和钾肥配比的产量最高,施肥成本、施肥利润、肥料投资效率分别为0.34万元hm-2、0.65万元hm-2和1.91万元,栽培效果明显优于其它配比。证明构建的模型准确可靠。     

江淮丘陵区水稻钾、氮吸收特性与施钾效应研究

江淮地区水稻田间小区施钾效应试验结果表明,施钾能明显提高水稻产量,改善水稻生育性状,在氮磷肥充足时,钾肥的增产效果极其显著。水稻钾吸收量明显以秸秆吸钾量为主,约为籽粒吸钾量的5倍。N来自土壤的数量为120.30 kg hm-2;K2O来自土壤的数量为72.83kg hm-2。NPK全素施钾处理吸钾总量平均高出NP处理48.79%,籽粒和秸秆分别平均增加9.21%和56.8%;说明钾吸收量增加对秸秆产量贡献明显小于对籽粒产量的贡献。除最高施钾量和不施氮处理外,其余处理均出现不同程度钾素亏缺,说明在不施氮肥或氮肥不足的情况下,水稻对肥料钾的吸收量也相应减少。本试验钾肥(K2O)产投比以NPK2处理最高为2.54。综上所述,本地区同等肥力土壤,水稻钾肥推荐用量为120kg hm-2,根据土壤钾素平衡状况,水稻施钾量可适当增加。     

淮北变性土区夏玉米对氮磷钾肥的响应特点研究

通过一系列的田间试验,研究了淮北变性土区夏玉米对氮、磷、钾的响应特点。结果表明:(1)玉米对氮肥反应十分敏感,施氮有极为显著的增产效果,一般可增产1倍以上。氮肥最佳用量在300 kg hm-2左右,分配比例以基肥和追肥各占50%的增产效果较好。氮肥追施时以“开穴深施”为宜,可提高其利用率;(2)玉米对钾肥反应较敏感,施钾一般增产15%左右,效果显著。钾肥适宜用量为90~180 kg hm-2,而且以基肥施入为宜;(3)玉米对磷肥反应不敏感,施磷增产效果不显著,但玉米仍表现为氮磷钾配合时产量最高。因此,提出“增氮、节磷、补钾”的玉米施肥原则。     

新垦淡灰钙土不同施肥定位试验初报

淡灰钙土是宁夏重点开发利用的耕地资源。针对新垦淡灰钙土土壤养分含量十分贫乏的问题,采取田间定位试验的方法,研究了新垦淡灰钙土4年不同施肥处理的增产培肥效应,结果表明:单施氮肥、有机肥和氮磷、氮磷锌及氮磷有机肥配施均有显著的增产作用。其中,施N225kg hm-2,较不施肥(对照)平均增产46.9%;施P2O5103.5~207.0kg hm-2,较单施氮肥平均增产31.3%,土壤速效磷提高1~2倍;每公顷第1年增施硫酸锌45kg hm-2的较氮磷配施平均增产7.7%,土壤有效Zn含量连续4年较氮磷配施提高1~1.5倍;增施羊粪11250~22500 kg的较氮磷配施平均增产14.1%,同时,土壤有机质含量较单施化肥提高30%左右。     

露地洋葱施肥、土壤养分及产量状况的分析研究

在农户调查和土壤测试相结合的基础上,分析了山东惠民县露地洋葱土壤养分状况、肥料投入及其对产量和养分平衡的影响。结果表明,施用有机肥农户占总调查户的44%,平均由有机肥带入的氮磷钾养分量分别为N 170kg hm-2、P2O5112 kg hm-2、K2O 223 kg hm-2。化肥氮、磷投入量较高,平均分别为N 458 kg hm-2和P2O5399 kg hm-2,是洋葱氮磷吸收量的4.0和6.0倍,化学钾肥不足(K2O 131 kg hm-2),占洋葱钾吸收量的55%。收获时0~30 cm土壤无机氮含量达到88 kg hm-2,O lsen-P(P)和速效钾(K)平均含量分别为25.5和104 mg kg-1。自春季返青前到收获期间,30~60 cm和60~90 cm土壤无机氮含量均有不同程度的提高,土壤氮表观损失量与氮素投入量呈显著直线相关,维持土壤氮素平衡的最大氮素供应量为290 kg hm-2。相关分析表明,无论是氮、钾化肥投入量还是各阶段土壤无机氮、速效钾含量都与洋葱产量无显著相关,而磷肥用量及0~30 cm土壤剖面O lsen-P含量与产量有显著正相关(p<0.05)。     

不同施氮量下北方稻田一次与分次施氮对水稻产量的影响

设计了适量和过量总施氮量下的一次和分次施氮的田间试验,研究了不同施肥方式对山西半干旱地区肥力水平较低的盐渍型水稻土水稻产量的影响.结果表明,适宜氮量(N 198 kg hm-2)下,水稻插秧前基肥一次性施氮较分三次在不同生育期施氮稻谷平均增产达10%;但过量施氮下,一次性基肥施氮较分三次施用平均减产6.6%.总施氮量小于适宜施氮量时,基肥一次性施氮较分三次施用平均增产则达到30%.插秧前基肥一次性施氮与基肥和分蘖初期分两次施氮相比,稻谷产量无明显差异.这说明插秧前和分蘖初期是该地水稻的有效施肥期.在不施磷肥或磷肥做基肥一次施用而氮肥分次施用的情况下,基肥氮磷施用比例也影响所施用氮肥的肥效;因此,就所试验的肥力较低的盐渍型水稻土来说,可以实行在减量施氮下的插秧前基肥一次性施氮,而不需要追施氮肥,并且在施P205130kg hm-2的条件下,总施氮190kg hm-2即可满足高产,因而可以减少习惯施氮量的1/3.     

黄花菜配方施肥技术研究

通过对黄花菜盆栽砂培试验、田间正交和氮磷肥单因素试验,研究了黄花菜配方施肥技术。结果是:黄花菜对N∶P2O5∶K2O三要素的最佳比例为2∶1∶2;对N、P、K三要素的总量以每亩40kg为宜(包括土壤供给量)。对不同肥力的土壤,每亩施用量的计算公式是:土壤中黄花菜可利用速效养分含量-每亩土壤速效性养分含量×黄花菜根系实际占用营养面积/栽培面积;在试验土壤条件下,要求施入N素9.5~1 3.5kg,P2O56.6~8.4kg;N、P单独施用,应酌量增加;N、P配合施用应适当减少;最佳的施肥时期是三月下旬一次施入。     

河西走廊制种玉米磷素适宜用量的研究

田间试验结果表明:河西走廊制种玉米NPK配合施用比NK配合施用增产25.30%.玉米产量随P素用量增加而增加,但单位P素增产效果则随P素用量增加而递减.经回归统计分析,P素经济效益最佳施肥量为60.15 kg hm-2时,玉米理论产量为9.75t hm-2,收入2.09×104元hm-2,p肥成本150.00元hm-2,收益2.08×104 元hm-2;在其它条件基本相同情况下,土壤速效P2O5含量5.71mg kg-1的风沙土,每kg P素玉米增产21.17 kg;而土壤速效P2O5含量11.23mg kg-1的灌漠土,每kg P素玉米增产13.50kg.处理间的差异显著性经LSR检验达到显著和极显著水平.     

钾肥对加工型番茄的肥效研究

田间试验结果表明:在速效K含量150.28mg kg-1的土壤上,番茄N、P、K配合施用比N、P配合施用增产11.56%。番茄产量随K素用量增加而增加,但单位K素增产效果则随K素用量增加而递减。经回归统计分析,K素经济效益最佳施肥量为225kg hm-2时,理论产量为113.53 t hm-2,番茄收入2.84×104元hm-2,肥料成本562.50元hm-2,收益2.78×104元hm-2,增收0.23×104元hm-2。在其它条件基本相同情况下,土壤速效K含量120.40mg kg-1时,每公斤K20增产番茄产品63.87kg;而土壤速效K含量176.26mg kg-1时,每公斤K2O增产番茄产品19.16kg。不同处理间差异显著性经LSR检验达到显著和极显著水平。     

黄土区村级农田土壤养分空间变异特征研究

本研究选择黄土高原地区陕西省新集村为研究对象。在219hm2耕地上用网格法采集364个表层(0~20 cm)土壤,研究了该村土壤pH,有机质和速效养分(N,P,K,Ca,Mg,S)空间变异性。结果表明:该村98.9%耕地缺N,缺K,缺P比例占11.5%和4.4%。地统计学分析结果表明:土壤有机质、有效N、P、K、Mg、Ca、S具有中等的空间相关性,空间变异程度依次为:OM>P>Ca>K>Mg>N>S,土壤pH的空间相关性很弱。有机质、有效N、S最大相关距离大,达到1853m,pH值最小,为148m,K、Ca、P、Mg最大相关距离分别为717m、720m、1032m和1344m。施肥是导致该村土壤养分空间变异性的主要原因。基于土壤养分状况和空间分布特征,目前仅需要考虑对该村土壤K,P进行分区管理。     

Probability 1 computation with chemical reaction networks

The computational power of stochastic chemical reaction networks (CRNs) varies significantly with the output convention and whether or not error is permitted. Focusing on probability 1 computation, we demonstrate a striking difference between stable computation that converges to a state where the output cannot change, and the notion of limit-stable computation where the output eventually stops changing with probability 1. While stable computation is known to be restricted to semilinear predicates (essentially piecewise linear), we show that limit-stable computation encompasses the set of predicates \(\phi :{\mathbb {N}}\rightarrow \{0,1\}\) in \(\Delta ^0_2\) in the arithmetical hierarchy (a superset of Turing-computable). In finite time, our construction achieves an error-correction scheme for Turing universal computation. We show an analogous characterization of the functions \(f:{\mathbb {N}}\rightarrow {\mathbb {N}}\) computable by CRNs with probability 1, which encode their output into the count of a certain species. This work refines our understanding of the tradeoffs between error and computational power in CRNs.     

氮钾肥施用量对秋季大白菜产量和品质的影响

通过研究不同氮、钾肥用量对秋大白菜产量和品质的影响表明:本地区常年蔬菜地种植秋季大白菜,氮肥(纯N)施用量宜控制在300kg hm-2以下,钾肥(K2O)用量150~225kg hm-2,氮钾肥施用比例1:0.5~0.8;氮肥用量增加植株内的亚硝酸盐含量提高,钾肥用量增加可相应降低大白菜体内亚硝酸盐含量;Vc含量则是随着氮钾肥用量的增加而提高;氮钾肥用量对大白菜容重也有较大影响,决定了大白菜的商品性状。     

Development and evaluation of a lightweight root cause analysis method (ARCA method) - Field studies at four software companies

Context

The key for effective problem prevention is detecting the causes of a problem that has occurred. Root cause analysis (RCA) is a structured investigation of the problem to identify which underlying causes need to be fixed. The RCA method consists of three steps: target problem detection, root cause detection, and corrective action innovation. Its results can help with process improvement.

Objective

This paper presents a lightweight RCA method, named the ARCA method, and its empirical evaluation. In the ARCA method, the target problem detection is based on a focus group meeting. This is in contrast to prior RCA methods, where the target problem detection is based on problem sampling, requiring heavy startup investments.

Method

The ARCA method was created with the framework of design science. We evaluated it through field studies at four medium-sized software companies using interviews and query forms to collect feedback from the case attendees. A total of five key representatives of the companies were interviewed, and 30 case participants answered the query forms. The output of the ARCA method was also evaluated by the case attendees, i.e., a total 757 target problem causes and 124 related corrective actions.

Results

The case attendees considered the ARCA method useful and easy to use, which indicates that it is beneficial for process improvement and problem prevention. In each case, 24-77 target problem root causes were processed and 13-40 corrective actions were developed. The effort of applying the method was 89 man-hours, on average.

Conclusion

The ARCA method required an acceptable level of effort and resulted in numerous high-quality corrective actions. In contrast to the current company practices, the method is an efficient method to detect new process improvement opportunities and develop new process improvement ideas. Additionally, it is easy to use.     

Pedal power for occupational activities: Effect of power output and pedalling rate on physiological responses

Because of the socio-economical conditions of farmers in developing countries including India, human muscle power is going to contribute energy requirements for performing many farm activities for the next two decades. Pedalling is the most efficient way of utilising power from human muscles. Pedal power enables a person to drive devices at the same or higher rate as that achieved by hand cranking, but with far less effort and fatigue. However, the use of pedal power for occupational work such as stationary farm operations has got scant attention in the past. Keeping these points into consideration a study was planned to optimise power output and pedalling rate for stationary farm operations. Physiological responses of 12 male subjects were studied on a computerised bicycle ergometer at five levels of power output (30-90 W) and seven levels of pedalling rates (30-90 rev min⁻¹). Analysis of data indicated that physiological responses were significantly affected with power output as well as pedalling rate. Increase in physiological responses (heart rate and oxygen consumption rate) over rest (delta values) were significantly higher when pedalling frequency was 30 rev min⁻¹ and above 50 rev min⁻¹. There was no significant difference between physiological responses at 40 and 50 rev min⁻¹. Physiological responses increased linearly with power output and were significantly different at different power outputs. The delta values of physiological responses at 60 W power output and 50 rev min⁻¹ pedalling rate (ΔHR = 40 beats min⁻¹ and ΔVO₂ = 0.56 l min⁻¹) were within acceptable limits for continuous pedalling work. From the results of the study it was concluded that for daylong pedalling work the power output from an Indian agricultural worker should be limited to 60 W and pedalling rate should be 50 rev min⁻¹.

Relevance to industry

The optimal power output and pedalling rate may be used for the ergonomic design of a dynapod or any pedalling device for efficient utilization of human muscle power with reduced drudgery and fatigue.     

三角梅

在贵州威宁县连续开展一系列的平衡施肥试验示范研究 ,研究结果认为 :最佳N、P2 O5 、K2 O施用以 10 4～ 150kghm- 2 ,60～ 90kghm- 2 ,150～ 2 10kghm- 2 或 10 0 :40～ 60 :14 0～ 150的配比合理 ,其肥料的产投比可达 7以上 ,钾肥在合理的配比情况下的产投比可达 10左右 ,钾肥的净收益可达 480 0元hm- 2 。试验证明平衡施肥可以使马铃薯的产量和收入比常产增加 1/ 3至 1/ 2 ,能提高商品品质 ,产生良好的社会经济效益     

长期施用无机NPK肥对保护地黄瓜光合特性及产量的影响

在长期单施无机氮肥(15年)条件下,黄瓜生长发育正常,而且随着施N量的增加(试验中的最高施N处理为每年600kghm-2),叶面积显著增大,叶片的叶绿素含量、光合速率显著提高,但处理间叶片胞间CO2浓度、气孔导度无显著差异,说明不同N水平对黄瓜叶片净光合速率的作用主要是由非气孔因素造成的,长期单施无机氮肥还显著地提高了黄瓜的产量、结瓜数、座瓜率,降低了畸形瓜率。N、P、K配施可进一步提高黄瓜叶片的叶绿素含量、光合速率、产量、结瓜数和座瓜率,降低畸形瓜率,但处理间叶片胞间CO2浓度、气孔导度仍无显著差异,说明不同N、P、K配施对黄瓜叶片净光合速率的作用主要也是由非气孔因素造成的。同时,在N、P、K配施试验中,以N对黄瓜光合作用及产量的影响最大,P次之,K较小。     

Ergonomics in developing hand operated maize dehusker-sheller for farm women

A hand operated maize dehusker-sheller to be operated by farm women was designed and developed to dehusk and shell the maize cobs using ergonomics (anthropometric, strength and physiological workload). Axial-flow maize dehusker-sheller with 540 mm cylinder length and 380 mm diameter required 3.03 N-m torque on cylinder shaft while operating at 5.6 m s(-1) peripheral speed and 100 kg h(-1) feed rate by feeding cob one by one. This torque was 30% of isometric torque obtained at front position of handle (greatest distance) with lowest crank length. The heart rate of subject while operating the maize dehusker-sheller at 54 rpm (5.6 m s(-1)) was 142 beats min(-1). The output of 60 kg h(-1) was obtained at the feed rate of 80 kg h(-1). Two subjects can operate the machine for an hour with a rest pause of 15 min by swapping the operation.     

Gender differences in the circadian variations in muscle strength assessed with and without superimposed electrical twitches

The circadian rhythm in muscle strength was analysed in 12 males (28 +/- 4 years, 79.6 +/- 12.3 kg, 1.80 +/- 0.05 m) and eight females (28 +/- 4 years, 60.3 +/- 5.5 kg, 1.61 +/- 0.08 m). After two familiarization sessions, participants were tested at six different times of the day (02:00, 06:00, 10:00, 14:00, 18:00 and 22:00 hours), the order of which was randomly assigned over 3-4 days. Rectal temperature (T(rec)) was measured over 30 min before each test. Peak isokinetic torques (PT) of knee extensors and flexors were then measured at 1.05 rad s(-1) and 3.14 rad s(-1) through a 90 degrees range of motion. Maximal isometric voluntary contraction (MVC) of knee extensors and flexors was measured at 60 degrees of knee flexion and the MVC of knee extensors was also assessed with superimposed electrical twitches (50 Hz, 250 V, 200 mus pulse width) in order to control for motivational effects. Three trials were performed in each condition, separated by 3 min recovery, and the highest values were retained for subsequent analyses. A significant circadian rhythm was observed for T(rec) in both males and females (acrophase, Phi, 17:29 and 16:40 hours; mesor, Me, 37.0 and 36.8 degrees C; amplitude, A, 0.28 and 0.33 degrees C for males and females, respectively). The mesor of T(rec) was higher in males than in females (p < 0.05). Significant circadian rhythms were observed for knee extensor PT at 3.14 rad s(-1) in males (Phi, 17:06 hours; Me, 178.2 N m; A, 4.7 N m) and for knee extensor PT at 1.05 rad s(-1) in females (Phi, 15:35 hours; Me, 128.7 N m; A, 3.7 N m). In males, the MVC of knee extensors demonstrated a significant circadian rhythm, but only when electrical twitches were superimposed (Phi, 16:17 h; Me, 302.1 N m; A, 13.6 N m). Acrophases of all indices of muscle strength were not statistically different between the two groups and were located in the afternoon (12:47 < Phi < 17:16 hours). The amplitude (percentage of mesor) of extensors MVC (electrically stimulated) was higher in males (6.4%) than in females (4.2%; p < 0.05). Significant circadian rhythms were not consistently observed for all indices of muscle strength whatever the gender. Our group of female subjects tended to show lower circadian amplitudes than the males. In males, maximal voluntary contraction of electrically stimulated muscles followed a circadian curve, which was not significant without the superimposed twitches. These results suggest that motivation could have a masking effect on the circadian rhythm in muscle performance and strengthen the view that peripheral factors are implicated in this rhythm.     

A pilot study to compare programming effort for two parallel programming models

Context

Writing software for the current generation of parallel systems requires significant programmer effort, and the community is seeking alternatives that reduce effort while still achieving good performance.

Objective

Measure the effect of parallel programming models (message-passing vs. PRAM-like) on programmer effort.

Design, setting, and subjects

One group of subjects implemented sparse-matrix dense-vector multiplication using message-passing (MPI), and a second group solved the same problem using a PRAM-like model (XMTC). The subjects were students in two graduate-level classes: one class was taught MPI and the other was taught XMTC.

Main outcome measures

Development time, program correctness.

Results

Mean XMTC development time was 4.8 h less than mean MPI development time (95% confidence interval, 2.0-7.7), a 46% reduction. XMTC programs were more likely to be correct, but the difference in correctness rates was not statistically significant (p = .16).

Conclusions

XMTC solutions for this particular problem required less effort than MPI equivalents, but further studies are necessary which examine different types of problems and different levels of programmer experience.