Ardiansyah@Biological and Environmental Engineering (BEE)

Menjawab Masalah Ketahanan Pangan, Dosen Fakultas Pertanian Teliti Padi Tanpa Genangan Air

[unsoed.ac.id, Rabu 4/1/12] Persoalan lahan yang semakin sempit, air yang ke depan akan semakin sulit, dan perubahan iklim tentu menjadi masalah yang cukup serius di sektor pertanian terutama pertanian tanaman pangan.  Salah satunya adalah padi.  Persoalan sempitnya lahan harus dijawab dengan peningkatan produksi, perubahan iklim menuntut pertanian yang ramah lingkungan, sementara semakin sedikitnya air menuntut sistem pertanian produksi tinggi dengan air yang sedikit.  Dahulu hal tersebut akan sulit diwujudkan, namun kali ini Dosen-dosen Fakultas Pertanian Jurusan Teknologi Pertanian berusaha mewujudkannya.  Tim penelitian yang diketuai Dr. Ardiansyah, S.TP.,M.Si, dan beranggotakan Arief Sudarmadji, ST.,MT, dan Ir Masrukhi, MP berupaya menjawab persoalan itu dengan melakukan penelitian ‘Pengembangan Teknologi Tepatguna dengan Sistem of Rice Intensification (SRI) untuk mewujudkan ketahanan pangan dan mengurangi efek perubahan iklim’.  Penelitian ini sudah dilakukan sejak Bulan Juli 2011 dan mulai menunjukkan hasilnya.

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How to Calculate Net Radiation for Vegetated Surface ?

How to Calcuate Net Radiation for Vegetated Surface

The following code written using Python. You will need OpenOffice Calc and oosheet to connect Python and OOCalc, so that Python can read/write values from/into OOCalc
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New Non-Destructive Method to Estimate Leaf Area Index in Vegetables

ScienceDaily (June 26, 2011) — The productivity and health of horticultural crops depends on the ability of the plant cover to intercept light energy. This ability is a function of the amount of leaf area, the architecture of the vegetation cover, and plants’ ability to convert light energy. One estimate of a crop’s ability to capture light energy is the leaf area index (LAI). Introduced in 1947, the concept of the LAI was defined as the ratio of leaf area to a given unit of land area. Today, understanding LAI is critical for successful crop management.
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1-Dimension Liquid Water Flow in Soil

(If equations don’t appear correctly, please go to this page)

Mass conservation equation :

Without Source/Sync :

Only considering liquid flow :

Figure 1. Discretization of pressure head (p) and flux (q) (Shiozawa et al., 2004)

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Water Hits And Sticks: Findings Challenge A Century Of Assumptions About Soil Hydrology

Water Online - January 25, 2010

Researchers have discovered that some of the most fundamental assumptions about how water moves through soil in a seasonally dry climate such as the Pacific Northwest are incorrect – and that a century of research based on those assumptions will have to be reconsidered.

A new study by scientists from Oregon State University and the Environmental Protection Agency showed – much to the surprise of the researchers – that soil clings tenaciously to the first precipitation after a dry summer, and holds it so tightly that it almost never mixes with other water.

The finding is so significant, researchers said, that they aren’t even sure yet what it may mean. But it could affect our understanding of how pollutants move through soils, how nutrients get transported from soils to streams, how streams function and even how vegetation might respond to climate change.

The research was just published online in Nature Geoscience, a professional journal.

“Water in mountains such as the Cascade Range of Oregon and Washington basically exists in two separate worlds,” said Jeff McDonnell, an OSU distinguished professor and holder of the Richardson Chair in Watershed Science in the OSU College of Forestry. “We used to believe that when new precipitation entered the soil, it mixed well with other water and eventually moved to streams. We just found out that isn’t true.”

“This could have enormous implications for our understanding of watershed function,” he said. “It challenges about 100 years of conventional thinking.”

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Menuju Solusi Krisis Pangan: Pengelolaan Blue Water dan Green Water Untuk Pertanian

English translation is here

Original article : http://io.ppijepang.org/article.php?id=340

Ardiansyah
Jurusan Teknologi Pertanian, Fakultas Pertanian,
Universitas Jenderal Soedirman (UNSOED), Purwokerto, Indonesia

Department of Biological and Environmental Engineering,
Graduate School of Agricultural and Life Science,
The University of Tokyo

1. Pendahuluan

Menurut Rost (2009), saat ini lebih dari 8000 km³/tahun air dikonsumsi untuk memenuhi kebutuhan pangan dunia (dalam bentuk evapotranspirasi, baik dari lahan tadah hujan maupun lahan beririgasi). Skenario IPCC’s SRES (Intergovernmental Panel on Climate Change – Special Report on Emissions Scenarios) menyebutkan, tambahan air sebanyak 5000 km³/tahun diperlukan jika populasi meningkat menjadi 10 miliar pada tahun 2050. Di samping itu, luas lahan pertanian saat ini yang sebesar 15 juta km² (sekitar 10% permukaan bumi) dianggap tidak akan mampu lagi mencukupi kebutuhan pangan. Masih menurut IPCC, keadaan ini berimplikasi pada diperlukannya ekspansi lahan sebesar 10 juta km² yang pada akhirnya diikuti oleh peningkatan kebutuhan air yang sangat signifikan. Lalu dari mana air tersebut akan diperoleh? Jawaban singkatnya adalah dari sumber-sumber air, sungai, danau, dan air tanah (groundwater).

Paradigma lama pengelolaan air hanya mempertimbangkan blue water (debit air sungai, danau dan air tanah). Umumnya dipahami bahwa penghematan air berarti menghemat penggunaan air yang diperoleh dari sumber-sumber tersebut sehingga menghemat pengambilan blue water. Penghematan air untuk keperluan domestik (rumah tangga) antara lain dilakukan dengan mengurangi penggunaan air yang tidak perlu. Namun, ketika berbicara masalah penyediaan pangan, tambahan air sebanyak 5000 km³/tahun mau tidak mau harus disediakan. Ini berarti eksplorasi besar-besaran terhadap blue water. Akan tetapi, untuk berbagai daerah yang mengalami masalah kelangkaan air (water scarcity), peningkatan konsumsi air bukan solusi sehingga diperlukan perubahan pola penggunaan air. Dengan hanya mempertimbangkan blue water, kita akan gagal dalam memecahkan masalah kelangkaan air untuk pertanian.

Green water Blue water Gb. 1. Konsep Blue Water dan Green Water

Tulisan ini akan membahas pentingnya mengintensifkan pengelolaan air untuk pertanian dengan mempertimbangkan green water. Selain itu perlunya diterapkan metode-metode baru dalam upaya konservasi green water serta penerapan teknologi Sistem Informasi Geografis dan pengindraan jauh (remote sensing) sebagai alat bantu pengelolaan sumber daya air. (more..)

Digital Images Estimate Canopy Coverage, Light Interception

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

Introduction to Mathematical Modeling of Crop Growth: How the Equations are Derived and Assembled into a Computer Program

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

honey

this is very beneficial book for the agricultural students

26 February 09 at 07:06

Crack in Paddy Field doesn’t Increase Water Loss

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

Drip Irrigation May Not Save Water, Analysis Finds

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)

caglar keskin

It is a useful information about drip irrigation. I am a farmer and we have very large fields, before drip ...

11 May 10 at 05:33