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November 2009

Welcome to the November 2009 edition of Fertile Minds, the newsletter of Sydney Environmental & Soil Laboratory.

In this issue we look at composting, pasture sampling, the nitrogen cycle and SESL in the community.

If you have any questions you would like answered in Fertile Minds, please write to info@sesl.com.au. If you have any special requirements, we would be pleased to talk with you and tailor a package and price. Please contact the office on (02) 9980 6554 or write to us at info@sesl.com.au.

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In this issue

• The Loam Ranger – SESL in the community: Narrabeen Sports High School
• Sampling pastures for nutrient analysis
• Composting
• The nitrogen cycle in soil
• Did you know ... ? – Gene for drought resistance found

The Loam Ranger – SESL in the community: Narrabeen Sports High School

In response to a phone call from a teacher at Narrabeen Sports High School looking for a lab that might be able to show some “science in practice” to students, Scott Fraser, who lives near the school, was invited to take the Year 9 science class on a field trip in the school grounds for a lesson in soil and water sampling.

Under Scott’s direction, students collected soil samples from the school’s playing fields and water samples from Narrabeen Creek. The samples were analysed back at the lab and at a couple of other labs, who also donated their time to the school.

The results should prove useful to the school. The key finding was that the soil of the playing field is heavily compacted and could be improved to support a top-quality playing surface. Regular treatment with a mechanical soil aerator several times a year in combination with topdressing with coarse sand over several years will gradually improve drainage.

The creek water analysis gives most cause for concern. Coliform bacteria, including E. coli counts, exceed the ANZECC recreational water quality guidelines for both primary contact, such as swimming, and secondary contact, such as boating and fishing. Creek water quality is outside the school’s influence, so unfortunately, the students will have to limit their field activities to visual observations.

Click here for full details (400 words, 2 minutes)

Sampling pastures for nutrient analysis

To get the most out of rotationally grazed pastures and to maximise livestock nutrition, testing your pasture for nutrient content is important. To compare results between paddocks and over time, you have to take and prepare pasture samples the same way every time. This article explains how to consistently collect pasture samples for nutrient analysis at the laboratory.

Click here to learn how to take pasture forage samples for analysis (750 words, 3 minutes)

Composting

Composting is the human technique of converting organic waste materials into soil improvers. It repeats, in a managed way, the natural process of biomass breakdown that sustains all life on Earth.

The key difference between natural breakdown and composting is that the process is deliberately optimised to maximise quality while minimising time. In all other respects, it is a natural process honed over billions of years.

Composting can take two forms: aerobic and anaerobic. Aerobic composting takes place in the presence of oxygen. This process is faster, hotter and nicer smelling. Anaerobic composting takes place in the absence of oxygen and is slower, cooler and foul-smelling. Ultimately, however, they both produce a useful product.

Click here for a backgrounder on composting (750 words, 3 minutes)

The nitrogen cycle in soil

Nitrogen (N) is the only plant nutrient that comes from the atmosphere. This complicates both its addition to a cropping system and its loss, but also makes it possible for some plants to obtain their own N.

N is absolutely essential to all life. In particular, it is an essential component of all proteins.

The following diagram shows the complexity of the N cycle. The main forms of N are shown in large black type. The stores of N are shown in small black type. The processes by which the N is transformed from one form to another are shown in pale blue. These processes are described below.

Click here for a description of each process (750 words, 3 minutes)

Did you know ... ? – Gene for drought resistance found

An international group of plant scientists led by Dr Gonzalo Estavillo and Professor Barry Pogson at the Australian National University have discovered a natural genetic mutation in plants that may make it possible to breed drought-resistant crops. The mutation, in a gene called SAL1, enabled plants to survive 50% longer without water than plants with the normal version of SAL1. Plants carrying the mutation produced higher amounts of various substances that protect plants against stress.

The team found SAL1 in a plant called Arabidopsis, which is the “fruit fly” of plant science. Many genes first found in Arabidopsis have later been found in other plant species, and SAL1 occurs in other important plant species, including wheat and rice. Therefore it should have the same function there too. It is now a matter of screening plants to find mutations with the same effect.

Click here to see why such a finding is critical for Australia’s future (350 words, 2 minutes)