Graeme Batten

A review of phosphorus efficiency in wheat

More efficient utilization of phosphorus by wheat plants is needed to extend the useful life of the phosphate reserves in the world, to reduce the cost of producing crops, and to improve the value of the grain and the straw produced. In this paper definitions of efficient use of phosphorus by wheat are reviewed, genotypic variation in phosphorus efficiency is reported, some consequences of breeding for greater efficiency are discussed, and ways to select more efficient genotypes are suggested.

Non-structural carbohydrate: Analysis by near infrared reflectance spectroscopy and its importance as an indicator of plant growth

Plant shoot samples are frequently analysed to assess if crops require additional nitrogen or mineral elements to maintain satisfactory growth. If plant growth is limited by temperature, water stress, disease, lodging or a mineral deficiency, non-structural carbohydrates (NSC) may be accumulated in, or depleted from, tissues especially those in the lower stems. Plant testing laboratories do not routinely analyse NSC to assist in the identification of plant stress probably because skilled technicians and time are required for the wet chemical determination. In this paper we report that routine determination of NSC is possible using near-infrared reflectance spectroscopy; the errors of determination are comparable with traditional chemical methods.

The potential of NIR spectroscopy to predict nitrogen mineralization in rice soils

Prediction of nitrogen (N) mineralization is important for specifying the optimum rate of N fertilizer for flooded rice at the time of sowing. To develop a predictive test, soils (0–0.1 m) were sampled from 22 farms throughout the rice-growing region of southern Australia over a 4-year period. Near infrared reflectance (NIR) spectra of the soils were compared with sixteen biological and chemical soil tests for the prediction of N-uptake by rice plants from these soils in the field and glasshouse. The aim of the study was to develop a soil-NIR calibration as an accurate, rapid and economical mineralization test. Nitrogen uptake by field-grown and glasshouse-grown plants was poorly correlated (r = 0.30), even though significant NIR calibrations were developed with both. Since N uptake by rice in the field was affected by varying weather and management, the field calibration is probably spurious. The calibration of soil NIR spectra with N uptake by glasshouse plants was satisfactory, with a standard error (SE) of 13 kg ha−1 over a range of 11 – 95 kg ha−1, and a correlation between calculated and measured N uptake (r = 0.87, P<0.001). An even better soil-NIR calibration was found with N-mineralization after 21 days of anaerobic incubation (SE 16 mg kg−1, range 52–175 mg kg−1). Analysis of the soil spectra showed that similar wavelengths were correlated with both plant-N uptake and mineralization. NIR spectroscopy shows considerable potential to predict soil N mineralization, and may assist future fertiliser decision support.

An appreciation of the contribution of NIR to agriculture

As the 20th century ends the world population approaches 6 billion people and is expected to increase to 8 billion by the year 2020. It is the responsibility of agriculture to provide food and fibre for all these people. Application of existing technology and innovation of new technology will be essential if agricultural scientists are to achieve this enormous task. In the 40 years to the present NIR spectroscopy has made major contributions to food and fibre production, and to the assessment of food quality and potential end-uses of produce. As NIR scientists we must strive to make contributions which help agriculture meet the challenge to feed and clothe the people of the world. The major challenge for NIR scientists in agriculture is maintaining sustainable yields, whilst reducing wastage and damage to the natural resource base. To have the greatest impact NIR-based technologies must be made available in developing countries at affordable prices. These challenges will involve developing and promoting options that are acceptable politically, sociologically and economically. NIR technology will provide the greatest benefits to feeding and clothing the worlds people if there is closer interaction with plant breeders, agronomists, environmentalists, food processors and marketers.

Near infrared technology for precision environmental measurements: part 1. Determination of nitrogen in green- and dry-grass tissue

The driving force for this work is rooted in data that confirms the contamination of streams and lakes caused from excessive use of nitrogen, pesticides and other soil amendments. Traditional analytical (wet chemistry) methods are too slow and too costly for detecting ecological abuse. A technology that would characterise the nutritional status of growing plants in a timelier manner (preferably in real time as an applicator moves through the field) is needed to control the volume of amendments. This paper explores the potential of near infrared (NIR) spectrometry for measuring nitrogen in plant tissue. In particular, it discusses the development of nitrogen calibrations, and performance of those calibrations, for both green- and dry-grass tissue. Results, based on collaborative studies by several researchers indicate that nitrogen can be measured with an SEP of 0.411% and 0.167% for green- and dry-grass tissue, respectively.

Nitrogen fertiliser alleviates the disorder straighthead in Australian rice

Straighthead is a ‘physiological’ disorder of rice, the symptoms being floret sterility, deformed florets and panicles and reduced grain yield. Straighthead in rice is difficult to investigate because of its unpredictable occurrence under field conditions. An experiment was conducted in south-eastern Australia in 1996 to investigate the effect of rate and timing of N fertilisation on growth and yield of rice. The presence of straighthead at this location gave a unique opportunity to study the influence of crop N status. This paper reports the influence of N application on straighthead symptoms during this experiment. A significant reduction of straighthead occurred with higher rates of N application. Application of 250 kg N/ha pre-flood, improved plant growth and vigour with subsequent increased uptake and accumulation of S, P, K, Mg, Cu, Mn and Zn in the plant at panicle initiation. The reduction of straighthead at high nitrogen rates may be due to improved uptake of several essential nutrients, and Cu may be a critical nutrient. This study and earlier observations have shown the application of optimal levels of pre-flood nitrogen to achieve grain yields greater than 10 t/ha may reduce straighthead severity in the Australian rice-growing environment. The results in this paper are not presented as recommendations to growers but a contribution to the currently limited literature on straighthead in Australia.

Measuring potassium in plant tissues using near infrared spectroscopy

Near infrared (NIR) spectroscopy is routinely used to determine constituents with organic bonds which absorb electromagnetic radiation in the region 1100 to 2500 nm. The nitrogen fertilizer requirements of cereal crops are determined from the analysis of vegetative samples by NIR spectroscopy. Simultaneous determination of other plant-essential elements would enhance the value of the analysis. Compared to nitrogen, other essential elements are either present at a lower concentration in the tissue or present largely in an inorganic form which is not detectable by NIR spectroscopy. In this paper we report NIR spectroscopic calibrations for potassium in grape petioles, grape leaves, rice shoots and orange leaves. When tested against a set of verification samples the NIR spectroscopic calibrations accounted for 96, 89, 93 and 85% of the concentration of K with standard errors of performance of 0.16, 0.12, 0.18 and 0.17%K respectively.

Impact of grinder configurations on grinding rate, particle size, and trace element contamination of plant samples

Abstract Samples of varying abrasiveness, including rice hulls, rice straw, wheat grain, orange leaves, and filter paper, were ground to pass a 0.5‐mm screen in two cyclone mills (Tecator Cyclotec model 1093 and Newport Scientific model 6200) with original and modified internal components. The ground samples were then digested in nitric acid and analyzed for 12 elements by Inductive Coupled Plasma (ICP) spectroscopy. Analysis of aluminum (Al), copper (Cu), iron (Fe), and zinc (Zn) showed that the amount of metal contamination from each mill was related to the abrasiveness of the plant material and the metal composition of the internal components of the mill. Least contamination was achieved using the Newport Scientific 6200 mill fitted with a stainless steel impeller and an abrasive steel strap with industrial diamonds set in pure nickel. For abrasive samples such as rice hulls a stainless steel impeller was about six times more durable than an aluminum impeller. The Newport mill ground samples in less ti...

Speaking Theoretically … Understanding Confusing Phenomena in Remission Spectra

T ake a look at Figure 1. What can you say about the relationship of the two samples? I imagine that you would say that Sample 1 (spectrum in bold) has a larger particle size than Sample 2, and that there is more of the material with characteristic absorptions around 1750 nm (marked by large arrow) in Sample 2. We’ll discuss first why we like your answer, and then we’ll tell you why you’re wrong. We are going to try to use a few different approaches in the hope of finding one you can relate to.

Plant Analysis. Widening horizons for plant analysis by NIR

Scientists at Yanco in southern Australia have pioneered the use of NIR analysis of rice and wheat crops so that farmers can assess the nutrient status of crops and decide if fertilisers would improve yield or quality of the grain. This article by Graeme Batten and Tony Blakeney, who have led this work from the beginning, explains that they have now expanded their horizons so that producers of other crops can benefit from the advances made in NIR technology.