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Accumulation ofSOCunderorganicandno-fertilizations,anditsinfluenceon crop yieldsinTanzania’s semiaridzone

Ecosystem Health and Sustainability 2018年第2期4卷 1-15页

作者： Msafiri Y.Mkonda Xinhua He Centre of Excellence for Soil Biology College of Resources and EnvironmentSouthwest UniversityChongqingChina Department of Geogr aphy and Environmental Studies Solomon Mahlangu College of Science and EducationSokoine University of AgricultureMorogoroTanzania School of Biological Sciences University of Western AustraliaCrawleyAustralia

Introduction:To estimate differential accumulation of soil organic carbon(SOC)and its ecological significance is very important to smallholder farmers in the Tanzania's semiarid areas.This study investigated the accumulation of SOC and other important soil nutrients under organic and no-ferti lizations,and correlated SOC with crop yields.Using data from long-term experimental study sites of semiarid in Tanzania,we estimated SOC accumulation in different soil treatments and depths where a total of 128 soil samples were collected at the depths of 0-20 cm and 20-40 cm from two villages(sites)with organic ferilization and no-ferilization treatments.Sites under organic fertilization were defined as those which have received manure fertilization for more than 5 years on continuum basis.Outcomes:The accumulation of SOC was significantly greater in soils under organic fertiliza-tions(1.15 and 0.80 MgC ha-'at soil depth and 20-40 cm)and decreased with increa sing soil depths.Similarly,TN and P decreased from 0.40 and 2.40 Mg(0-20 cm)to 0.16 and 2.10 Mg(20-40 cm),respectively.Other important soil nutrients such as calcium(Ca^(2+)),potassium(K^(+)),magnesium(Mg^(2+)),and sodium(Na^(+))had similar patterm.In addition,soil bulk density was less under organic fertilization(1.1 g/cm^(3))than under no fertilization(1.2 g/cm^(3))and it increased with soil depths.Correspondingly,the crop yields were significantly higher(1.6 tn ha^(-1))under organic friliations than(0.6 tn ha^(-1))under no-fertilizations indicating that crop yields were significantly affected by SOC.Discussion:Organic fertilization i.e.,especially cattle manure in the area has considerable fertility potential.To optimize soil fertility potential,we need to consider such kind of ferilization from household to national level.Conclusion:Our results demonstrated that manure application was the best ferilization method for improving soil fertility in most croplands of Tanzania's semiarid areas,especially in this era of climate change scenarios.

关键词： Agriculture ecosystems environment farm management semiarid Tanzania

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Evaluation of Replacement Policies in Sow farms Using Arena^(TM) Simulation Software

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Intelligent Control and Automation 2014年第3期5卷 126-135页

作者： Marco Antonio Montufar Benitez Luis M.Pla Aragones Marco A.Serrato Garcia Oscar Montano Arango Jose Ramon Corona Armenta Academic Area of Engineering Autonomous University of HidalgoPachucaMexico University of Lleida LleidaSpain Tecnologico de Monterrey Campus TolucaTolucaMexico

This paper presents an application of the simulation of discrete events (SED) using ARENATM in the management of large-scale breeding farms. The main objective of the simulation model is to find a policy of replacement, to ensure the best economic performance of a farm. The only variant analyzed of replacement policy was the number of cycles set in permanency for a sow in the herd. Considered incomes come from the sale of piglets and unproductive sows, and costs are due to the feeding of animals, replacement sows purchases, and the operation expenses of the farm. For this analysis, the production process was divided into three major stages called: mating, pregnancy or gestation and lactation. The sow’s movement from one stage to other was modeled by cycle-dependent transition probabilities. Considering the daily utility, as response variable, the model shows the best number of cycles to maintain the sows.

关键词： Simulation ARENA^(TM) farm management Sows Replacement

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