Ardiansyah@Biological and Environmental Engineering (BEE)

ScienceDaily (Feb. 17, 2009) — Canopy light interception (LI) is an important factor for crop growth and fruit yield. Crop yield depends on a canopy’s ability to intercept incident solar radiation, which in turn depends on the available leaf area, its structure, and its efficiency in the process of photosynthesis.

Maximizing leaf growth through light interception is an important consideration when studying different agricultural or environmental factors on crop yield, and it is the main source of data in the most widely used methods for estimating crop water needs.

A study conducted by C. Campillo, M.H. Prieto, C. Daza, M.J. Monino, and M.I. Garcia, and published the October 2008 volume of HortScience, looked at how digital images can characterize canopy coverage and light interception in processing tomato crops. Digital images offer a series of advantages over other methods of LI estimation, including the possibility to directly process images by computer using free software.

According to Campillo, “The objectives of the study were to develop a simple, economical method for determining LI in low-lying crops such as processing tomato using digital images obtained with a standard, commercial camera and free software and to evaluate the influence of different types of soil coverage (bare soil and plastic mulch) on canopy light interception.”

The resulting images were processed and analyzed using the free software GIMP 2.2 and IMAGE J. Three different methods were used in the analysis: soil area (SA), soil contour (SC) and reclassification (SR), in order to quantify the percentage of groundcover (PGC). A close relationship between LI and estimated PGC was found with all three methods and for different soil cover regimes.

Many practical advantages to the methods were found. Most important, stated the researchers, measurements using a digital camera can be taken at any time of day, and bright sunshine is not necessary. In contrast, another common method that uses active radiation bars for measurement must be taken at solar noon and requires bright sunlight for accurate results.

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Further reading :

Campillo, C., Prieto, M.H., Daza, C., Monino, M.J., Garcia, M.I. Using Digital Images to Characterize Canopy Coverage and Light Interception in a Processing Tomato Crop. HortScience, 2008 43: 1780-1786

Learning mathematical modeling need not be difficult. Unlike other books, this book not only lists the equations one-by-one, but explains in detail how they are each derived, used, and finally assembled into a computer program for model simulations. This book shows how mathematics is applied in agriculture, in particular to modeling the growth and yield of a generic crop. Topics covered are agriculture meteorology, solar radiation interception and absorption, evapotranspiration, energy and soil water balance, soil water flow, photosynthesis, respiration, and crop growth development.

Read further about this book here

As the demand of water from various sectors will increase along with advance in development, water productivity in agricultural sector (amount of rice grain per water use) should also increase so that less water will produce the same amount yield or even more. Minimizing water loss is one way to increase agriculture water productivity.

Clay soil is typical of paddy field soil in Banten area, West Java-Indonesia. This area is part of tropical monsoon region, in which the rainy season and the dry season is explicitly distinguishable. In dry season, where water shortage occurs, paddy field dries and soil surface shrinking. Cracks are formed in the paddy field as soil dries.

Figure 1. Crack pattern in paddy field. (a.) Dry paddy field with crop plant residue and cracks. (b.) Image of a. which thresholded for soil surface and cracks only. Crack opening is 16% of surface area.

People might think that crack opening will broaden the surface of evaporation and increase water loss as similar as evapotranspiration occurs in the cultivated paddy field. However, measurement shows that this thinking is not correct, at least in this type of soil. Evaporation reduces in the same way that when the soil has no crack. How this could happen? It is consider that the cracks can be regarded as insulated spaces for heat conduction and also for heat convection. Thus the heat entering crack surface is not significant amount because it should through the insulation layers. On the other hand, the heat in the soil surface is come from direct sunshine radiation, not from conduction or convection as in crack does.

The other reason is that vapor conductivity of dry clay soil is very low so that it can reduce evaporation up to 50% even though dry layer thickness is only several mm. Evaporation/Evapotranspiration should considered as water loss if it is not contribute to rice productivity. Productive paddy field evaporates water, however in dry season some unproductive paddy field still create water loss through surface evaporation and subsurface root water uptake

Lowland paddy field in Indonesia is dominated by clay soil which shrinking and swelling according to dryness level. This finding will open several new research ideas on increasing water productivity in clay paddy field soil.

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Further reading : Thermal Properties and Shrinkage-Swelling Characteristic of Clay Soil in a Tropical Paddy Field

Published: November 17, 2008

In an effort to make irrigation more efficient — to obtain more “crop per drop” — farmers have adopted alternatives to flooding and other conventional methods. Among these is drip irrigation, shown above, in which water flows only to the roots. Drip systems are costly, but they save much water.

Or do they? A hydrologic and economic analysis of the Upper Rio Grande basin in the Southwest, published in The Proceedings of the National Academy of Sciences, suggests that subsidies and other policies that encourage conservation methods like drip irrigation can actually increase water consumption.

“The take-home message is that you’d better take a pretty careful look at drip irrigation before you spend a bunch of money on subsidizing it,” said Frank A. Ward, a resource economist at New Mexico State University and author of the study with Manuel Pulido-Velázquez of the Polytechnic University of Valencia in Spain.

With flood irrigation, much of the water is not used by the plants and seeps back to the source, an aquifer or a river. Drip irrigation draws less water, but almost all of it is taken up by the plants, so very little is returned. “Those aquifers are not going to get recharged,” Dr. Ward said.

Drip irrigation also generally increases crop yields, which encourages farmers to expand acreage and request the right to take even more water, thus depleting even more of it. “The indirect effect is very possibly to undermine policy attempts to reduce water consumption,” Dr. Ward said.

Policymakers, he added, must balance the need for more food and for farmers to make a living with water needs. “It’s fair to say that subsidies are very good for food security and very good for farmer income,” Dr. Ward said. “But they may be taking water away from other people.”

(source : http://www.nytimes.com/2008/11/18/science/18obwater.html?_r=1)

Contributor : Rudiyanto

Measurement is about quantifying of object property, therefore we should consider how stable and reliable data we got from measuring activity. Recently, computer technology enable us to interface between physical world and digital world. However, reliability of data and stability in our measurement system sometimes resulting undesirable outcome which difficult to analyze. This presentation file introduce us to basic data acquisition and filtering data using Kalman filter.

Download File : Pengantar Data Akuisisi dan Kalman Filter

Contributor : Rudiyanto

In highly non-linear system which difficult to recognize, such as in meteorological even, data learning method is powerful tool to analyze relation among parameters. This handout will bring us to understand what is inside Artificial Neural Network, one of data learning method.

Download File : Backpropagatioan ANN

Contributor : Satyanto Krido Saptomo

Pada experimen kali ini ada beberapa parameter yang harus didapatkan untuk digunakan dalam eksperimen simulasi aliran air dalam tanah. Parameter-parameter tersebut adalah:

1. Volumetric water content (kadar air volumetrik).
2. Permeability/saturated hydraulic conductivity (permeabilitas atau konduktivitas hidrolika pada kondisi jenuh air).
3. Hydraulic conductivity (konduktifitas hidrolika, mengacu pada kondisi tidak jenuh air).
4. Tension / pF (tekanan negatif/hisapan tanah).

Kadar air volumetrik (1) diukur untuk semua sampel, di mana setiap sampel diambil pada kedalaman tanah yang berbeda dan akan merepresentasikan kadar air di lokasi tersebut pada setiap kedalaman. Untuk pertama kali ditimbang berat sampel (tanah beserta ring sampel dan kedua tutupnya), ini selalu dilakukan di awal sebelum perlakuan lainnya diterapkan pada sampel tersebut. Pada pengukuran pF akan diperoleh juga jumlah air dalam tanah untuk setiap pF tertentu. Permeabilitas diukur dengan metode ‘falling head’ dimana di atas sampel tanah diberikan suatu kolom air dengan ketinggian head tertentu. Kemudian waktu dan jarak ‘jatuh’permukaan kolom air tersebut diukur, sehingga akan diperoleh nilai permeabilitas dalam satuan jarak per waktu. Tentu saja ada hitungan khusus sesuai dengan alat yang dipergunakan dalam pengukuran.

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Accomodating as many as possible scientist and engineer to share their ideas/concept could make this website useful to others. But oftenly, we have to face the obstacle that typing is boring, especially when your concept is full of math symbols and formulas. Therefore it is enjoyable if they should only scan their originally hand-sketch work paper, add some comments on it, and just post to this website.

If you’re scientist and want to share your knowledge (whether it is concept, idea, published paper or laboratory setting for experiment) to others, but you don’t have time to type, just send us one of the following :

1. Scan image of your concept, hand-sketch are also welcome.
2. Your previous published paper
3. Anything related to this field of study

What we are going to do is :

1. Making PDF of your manuscript.
2. Create one entry for your manuscript in this website.
3. Add small introduction to this entry, and off course we will write your name as contributor.
4. Put PDF file to this entry so that if people interested to read your manuscript (after reading introduction part), they can just click on the link to read your manuscript

or maybe I have enough time to copy your manuscript and show all image to one entry, so that people can just read it directly without embedded Acrobat Reader in their browser.

Happy writing, reach your happiness by sharing knowledge !!

Climate Under Cover
Digital Dynamic Simulation in Plant Bio-Engineering
Takakura, Tadashi, Wei Fang
2nd ed., 2002, 204 p., Hardcover

ISBN: 978-1-4020-0845-0

This book gives a full description of the simulation techniques used in the greenhouse industry, including different environments from mulching to greenhouses. Another important topic discussed at length is the relationship between plants and the environment. An emphasis is put on the relationship between quantitative phenomena and qualitative analyses. Most of the phenomena involved are non-linear and non-steady-state. In this second edition we describe these phenomena with an approach called System Dynamics and mathematical models developed in the simulation languages MATLAB and SIMULINK. These models can be easily adapted to the specific requirements of the readers, and the environments in which they work. In general, the subjects covered in this book are relevant to graduate students, scientists, and researchers in the agricultural and biological sciences. This book is a valuable addition to libraries of agricultural organizations and individual professionals in both developing and developed countries.

Contents
1. Introduction
2. Definition of covering and properties of covering materials
3. Digital Simulation
4. Heat Balance of Bare Ground
5. Solar Radiation Environment
6. Temperature Environment Under Cover
7. Carbon Dioxide Enviromnent
8. Water and Vapor Environment
9. Control Function
10. Plant Response to The Environment

Important notes :
When you decide to explore this book, make sure that you are familiar with Matlab programming language. This book is not like any other text book which include formulas written in their original form. Instead it the formula is written in code, which make you put a little effort to match with the original form that you already recognize.
This book is accompanied with CD contains all the programs created for each chapter. The result of the program and the code is appear in the book, and you still can have experience to trace the original program from the original code. You should have Matlab installed in your computer.