Determination of soil salinity based on WET measurements using the concept of salinity index

We evaluated the Malicki and Walczak model (MW) and its appropriately modification (MMW) in the prediction of the electrical conductivity of the soil solution (σ_p), utilizing the WET dielectric sensor. In the MMW approach, the prediction of σ_p requires determination of the WET‐based salinity index (X_s) and clay and sand contents of the soil. MMW appears to be more effective than MW in all cases except for the cases of finer soils when σ_p > 3 dS m^?1.     

Fleets of robots for environmentally-safe pest control in agriculture

Feeding the growing global population requires an annual increase in food production. This requirement suggests an increase in the use of pesticides, which represents an unsustainable chemical load for the environment. To reduce pesticide input and preserve the environment while maintaining the necessary level of food production, the efficiency of relevant processes must be drastically improved. Within this context, this research strived to design, develop, test and assess a new generation of automatic and robotic systems for effective weed and pest control aimed at diminishing the use of agricultural chemical inputs, increasing crop quality and improving the health and safety of production operators. To achieve this overall objective, a fleet of heterogeneous ground and aerial robots was developed and equipped with innovative sensors, enhanced end-effectors and improved decision control algorithms to cover a large variety of agricultural situations. This article describes the scientific and technical objectives, challenges and outcomes achieved in three common crops.     

东北大豆品种资源筛选

近年来,随着国内对大豆需求的增加,大豆科技投入长期不足,大豆单产提高缓慢,使中国大豆供需矛盾日趋突出。大豆新品种的选育,一直是育种家们长期以来的目标。优良品种是大豆高产的基础。在选择大豆品种时,要因地制宜,尽量选用适合密植、抗病虫害、抗倒伏的优良品种,同时要符合当地的气候特征和耕作条件。笔者通过从572 份东北大豆品种资源中筛选出黑龙江省第二积温带生态区适应性较为突出的50 份材料,进一步了解50 份育成品种的遗传结构、遗传背景及各品种之间的亲缘关系,品种在各个区域的适应性能力,为优异种质资源的创新与利用提供理论指导,为新品种选育提供信息。     

氮、磷、钾配比施肥对辣木生长及叶片养分吸收的影响

[目的]为明确辣木生长对养分的需求及叶片养分吸收状况。[方法]研究采取田间小区实验,设置N_(80)、N_(80)P_(20)、N_(80)K_(40)、P_(20)K_(40)、N_(80)P_(20)K_(40)、N_(60)P_(20)K_(60)和不施肥对照7个处理,测定分析不同氮、磷、钾配比施肥对辣木生长及叶片养分吸收的影响。[结果]不同氮、磷、钾配比施肥处理下,辣木生长速度先快后缓慢,处理90 d后株高、冠幅和鲜叶生物量的最高值及地径的次高值均出现在N_(80)中,N_(60)P_(20)K_(60)的株高、地径及N_(80)K_(40)的鲜叶生物量仅次于N_(80)处理;不同氮、磷、钾配比施肥均促进了辣木叶片中全氮、全磷含量的累积,但降低了全钾含量;除N_(80)外,其它处理叶片叶绿素含量均低于CK,高氮处理的叶绿素含量均高于P_(20)K_(40)和N_(60)P_(20)K_(60),N_(80)P_(20)高于N_(80)K_(40)。[结论]各元素对辣木生长影响大小为NKP,对叶片中叶绿素含量影响大小为NPK,叶片中营养元素含量大小为NKP。综合试验结果中辣木主要生长指标的生长及叶片养分吸收情况,配比施肥最优处理为N_(80),且该施肥处理主要适用于辣木幼龄及速生生长阶段。     

根瘤菌与微肥对大豆生理及产量的影响

为促进大豆生产过程中根瘤菌和微肥的合理使用,采用根瘤菌、微肥、根瘤菌+微肥、对照4个处理,在大豆苗期(V3)、盛花期(R2)、盛荚期(R4)、满粒期(R6)对大豆叶片的叶绿素含量、可溶性糖含量、可溶性蛋白含量进行测定;在大豆成熟期对产量及相关农艺性状进行测定。结果表明:根瘤菌和微肥的使用在大豆不同生育期,一定程度上增加了大豆叶片叶绿素、可溶性糖及可溶性蛋白含量;产量结果表明:无论是单独施用根瘤菌、单独施用微肥或根瘤菌和微肥同时施用均可提高大豆产量,与对照相比根瘤菌+微肥处理产量为2 643.07kg·hm~(-2),在各处理中产量最高,与对照相比增产26.02%;根瘤菌处理增产18.33%;微肥处理增产21.73%。     

Potential Use of Hibiscus Rosa-Sinensis Leaf Extract for the Destabilization of Turbid Water

In the present study, the ability of Hibiscus rosa-sinensis leaf extract (HLE) to act as a natural coagulant for the water treatment was tested. Synthetic turbid solutions were prepared using kaolinite, and the efficiency of HLE was examined for low and high turbid solutions. HLE was very effective in high turbid solutions than in low turbid water and follows enmeshment mechanism of destabilization. An insignificant effect of alkalinity on the performance of HLE was observed. The addition of NaCl increased the dissolution of coagulation active species and enhanced the efficiency of HLE, significantly. Hydroxyl and carboxyl groups present in HLE were the major functional groups responsible for the bonding between coagulant and kaolinite. The efficiency of alum was very high compared to that of HLE in both turbid solutions. But the optimal dosages of HLE were lesser than that of alum. Thus, HLE can be used as a coagulant aid for the effective treatment of water.     

Dry cultivation enhances cadmium solubility in contaminated soils but minimizes cadmium accumulation in a leafy vegetable

Purpose

Water management has a strong influence on Cd solubility in agricultural soils, affecting Cd uptake in crops. In the process, sulfur interaction with other metals such as zinc may play an important role. A pot experiment was carried out to investigate the effects of water management coupled with zinc and sulfate amendment on Cd uptake by the leafy vegetable amaranth with a strong Cd accumulation tendency in its edible parts.

Materials and methods

The soils were amended with Cd, Cd+SO₄ and Cd+SO₄+Zn with no amendment as control. Then, the soils were flooded for 1 month, after which amaranth was grown with soil kept saturated (wet cultivation). In the succeeding planting, soils were tilled to aeration condition under which amaranth was grown again (dry cultivation). Soil and crop samples were collected and analysed for various parameters.

Results and discussion

The readily exchangeable quantities of Cd and Zn in the soil decreased under wet cultivation, increasing again under dry cultivation but to levels lower than those in the initial soil. Wet cultivation enhanced plant Cd concentration but reduced Zn accumulation compared to dry cultivation. Zn bioavailability was strongly affected by soil water status but failed to reduce Cd uptake by amaranth. Irreversible or slowly reversible changes occurred in Cd and Zn solubility and phytoavailability as soil water-saturated status was altered by periodic flooding events.

Conclusions

Dry cultivation with lower soil water content ensured high production with low Cd in the edible part of this leaf vegetable and so remains the recommended irrigation regime.

     

The sorption of water vapour of wood treated with a nanotechnology compound

The potential of improving the hygroscopicity of solid wood by applying a new nanotechnology compound was investigated. The sorption isotherms were analysed using the Hailwood–Horrobin model. The experimental analysis of the sorption isotherms showed that the treatment affected total, polymolecular and monomolecular sorption. The application of the compound reduced the total sorption by 26.5%, polymolecular sorption by 23.9% and monomolecular sorption by 33.1% at saturation.     

Development and evaluation of a guayule debarker

Guayule (Parthenium argentatum Gray) stores its rubber primarily within the cells of its bark, which constitutes only 30% of the dry weight of the whole shrub. Debarking guayule soon after harvesting at the crop site would substantially improve the efficiency of latex extraction technology by reducing transport costs to the processing plant and increasing the processing capacity of the latex extraction plant. The objective of this study was to design, fabricate and evaluate an efficient debarking machine for guayule. The bark removal unit consists of a pair of grooved rubber rollers rotating in opposite directions at different speeds, drawing and crushing the cut stems without chipping the core. The clearance between the rollers is adjustable and can handle different stem sizes ranging from 6 to 45 mm. The speed difference between the rollers creates a shearing action, required for peeling the bark. The separation unit consists of a fan attached to metal tubing, a discrimination chamber for grading processed material and a water trough where lighter material is removed by flotation. The debarking system was tested to determine bark removal performance as well as separation of bark from other processed plant material. A debarking efficiency of up to 95% and maximum separation efficiency of 75% were found from the evaluation. The prototype debarking machine produced a throughput capacity of up to 450 kg/h which can be increased by converting it to a full-size field machine.