Gordon Rajendram the soil scientist

April 2020

Nitrogen fertiliser trial database: a valuable resource. Climatic factors and first cut response to nitrogen application.

G.S. Rajendram, J. Waller, C. Cameron, R. Longhurst, J. Luo, A. Ghani and M. O’Connor. AgResearch, Ruakura Research Centre, East St, Private Bag 3123, Hamilton. Abstract Data from 1,272 nitrogen (N) fertiliser trials from around New Zealand over the last 80 years were collated onto an electronic database.  Data collected included nitrogen (N) fertiliser forms, N application rates, plant dry matter (DM) yields, botanical composition, soil types and weather conditions (rainfall and air temperature).  These data were sourced mostly from original trial records and reports.   In this paper, a summary of the information gathered from the database and relationships between the first cut N response and climatic factors are presented. Nitrogen response was calculated as the extra daily kg of plant DM produced per kg of N applied. Most of the trials either used Nitrolime or Urea. A comparison of N responses between these two fertiliser products showed no significant overall difference. Late spring application gave the greatest and most reliable response to N application. In general, only weak relationships between climatic factors and response to N were established.  The strongest relationship was found to be between response and average daily air temperature for each soil, under near-ideal conditions (average daily rainfall ≥ 1 mm and soil deficit ≤ 20 mm) where basal fertiliser had been applied.  The relationship between N response and rainfall was weaker than the relationship between N response and temperature. An estimate of minimum average daily air temperature for an N response in spring was established as 5 0C and is consistent with overseas studies. This suggests that fertiliser should not be applied until the daily mean air temperature is > 5 0C. However, using data currently available, no single relationship has explained pasture response to applied N fertiliser application; perhaps not surprisingly.  Better correlations may have been established for N response if more soil moisture or N status data were available and basal fertiliser application included more frequently in trial design. Only a few trials had soil moisture and N status data. Many trials, approximately 50%, did not have basal fertiliser applied. If any major or trace elements did limit pasture growth, this may have affected the magnitude of N responses. Some of the factors confirmed as influencing N response are temperature, soil type soil moisture and basal fertility. Therefore, a fertiliser decision support system needs to take into account at least these factors. This database represents a useful resource complementing future investigations. Introduction Nitrogen (N) fertiliser trials have been conducted in New Zealand over the past 80 years. The major organizations involved in N research have been MAF, MAFTech, and AgResearch. The DSIR also carried out several field trials on N during the 1970-80s.  Approximately one-third of the N response trials conducted in NZ were carried out by O’Connor and his team at MAF between 1969-1975 (O’Connor, 1982).  After MAFTech and the DSIR were disbanded, commercial fertiliser companies such as Ballance Agri-Nutrients and Ravensdown have provided the funding for most of the N research conducted since the mid-1990s until present, using technical expertise within the Crown Research Institutes and Universities to conduct trials. There have been numerous publications on the use of N fertiliser to pastures in the form of booklets and short articles, such as ‘N fertiliser use on pastures and crops’ (Ledgard, 1990’s); AgFact (Crush et.al., 1994) and ‘Fertiliser use on NZ dairy and sheep and beef farms’ (Roberts et. al., 1993). The findings from this study will help in part to develop ‘a decision support tree’. The purpose of the decision support tree is to ensure efficient N fertiliser use for desired environmental and production outcomes under New Zealand climate and soil conditions. The data obtained will also be useful for further improving the Overseer nutrient budget model. Method Field trials conducted throughout New Zealand have generally used the experimental designs and procedures outlined by Lynch (1966). First, data from all these field trials were obtained, collated, and entered into an electronic database. Climatic data from the nearest meteorological station were also included to assist the interpretation of the results.  Data were later selected and statistical analysis undertaken.  This paper presents information gained from the N trials and parameters used for setting up the database.  The data were used to establish relationships between N response and climatic factors and a summary of this analysis is presented. Statistical Methods Much of the basic analysis was carried out in Excel, filtering the graphs according to various regimes: No summer months were used in the analysis of the data, as there were concerns over potential issues with sward composition.  Trials where the control plot yields exceeded 5,000 kg DM/ha and where the days of growth did exceed 100 were excluded. There was a range of fertiliser products used. This study will consider only Nitrolime and Urea, the most common products by far.  A discussion of the difference between the two is presented in the discussion section. Summaries of the regressions as well as the best models are provided in the Results and Discussion section.  Note that these regressions are probably best described as ‘explanatory’ rather than ‘predictive’ models.  Measure of Response Data were restricted only to first cut response for this study.  In this report, the 50 kg N/ha rate is used to calculate the daily kg DM produced per kg of N applied. The measure of response considered in this study is “unit N”, which is defined as: ‘the increase in rate of growth per unit N applied’. Unit N = (Treatment Yield – Control Yield) / N Applied (kg) / Days of growth Yields are expressed as kg dry matter (DM). N applied is expressed in kg. Trials in the database did not always have a 50 kg N/ha rate. In order to include the vast majority of trials in the database for this report, application rates in the range 40-60 kg N applied were used. This requires that approximate linearity of the response be assumed over this range, a feature

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EFFECT OF RATE OF NITROGEN FERTILISER ON CATION AND ANION LEACHING UNDER INTENSIVELY GRAZED DAIRY PASTURE

G.S. Rajendram1, S.F. Ledgard1, R. Monaghan2, J.W. Penno3, M.S. Sprosen1 and L. Ouyang1 1AgResearch, Ruakura Research Centre, Private Bag 3123, Hamilton 2AgResearch, Invermay, PO Box 50034, Mosgiel 3Dairying Research Corporation, Private Bag 3123, Hamilton Abstract Losses of Ca, Mg, K, Na, nitrate-N, sulphate-S, Cl and inorganic P were determined in intensively grazed dairy pastures at three sites receiving no nitrogen fertiliser. The range of losses for each nutrient in kg/ha/year were 69-144, 10-46, 6-16, 32-79, 21-26, 39-89, 63-123 and <1 respectively. Measurements of leaching losses relative to nutrient inputs in fertiliser, rainfall and drench at DRC Number 2 dairy indicated that leaching of Mg exceeded inputs by approximately 20 kg/ha/year. Leaching losses of the above cations and anions were also measured in dairy cow farmlets at DRC Number 2 dairy which received 0, 200 or 400 kg N/ha/year. The amount of nitrate-N leaching increased with increasing rate of N fertiliser application. This was associated with an increase in leaching of Ca of up to 100%. There was no significant effect on leaching of other cations. Introduction In New Zealand, there have been few studies on the leaching of anions and cations in intensive dairy farming systems. Charge balance needs to be preserved in leaching solutions and therefore a cation will accompany any anion leached. The leaching of anions and cations will be dependent on a number of factors including the amounts and form of nutrients applied in fertiliser, stocking rate, drainage, soil type and extent of previous leaching (McLaren and Cameron, 1990; Scholefield et al., 1993). With the increasing use of N fertiliser on dairy farms over the past 5-10 years, there has been increasing concern about the impact on nitrate leaching to groundwater. Ledgard et al.(1996) showed that increased N fertiliser application on dairy pasture resulted in increased nitrate-N concentrations in groundwater. Leaching of nitrate also results in leaching of associated cations and this has implications to the requirements for nutrients in the farm maintenance fertiliser programme and to the lime requirement (Sinclair et al., 1993). The aim of this study was to determine the amounts of Ca, Mg, Na, K, nitrate-N, sulphate-S, Cl and inorganic P leached from intensively grazed dairy pasture at 3 sites in the absence of N. In addition, nutrient leaching was determined in dairy farmlets at one site receiving 0, 200 or 400 kg N/ha/year. Method Farmlets receiving no nitrogen fertiliser 1. Waikato farmle Cation and anion losses were measured in 1995 in a farmlet at the Dairying Research Corporation (DRC) No. 5 dairy which received no N fertiliser. Soil solution at 1 metre depth was collected using 30 ceramic cup collectors at 2-3 weekly intervals ( Sprosen et al., 1997). Calcium, Mg, Na and K were analysed using atomic absorption spectroscopy, nitrate-N using flow injection autoanalyser, sulphate-S using high pressure ion chromatography, and chloride using uv/vis spectroscopy. The farmlets were rotationally-grazed by dairy cows. The soil type was a moderately-well drained Bruntwood silt loam (Aquic Hapludand) derived from volcanic ash. Drainage was estimated from the volume of water passing through lysimeters (0.4 m diameter by 1 m depth) containing intact soil cores. Data for drainage and nutrient concentrations were used to calculate the amount of nutrients leached. 2. Southland farmlet Leachate from mole and tile drains was collected at frequent intervals from 6 non-N-fertilised paddocks (Monaghan, unpublished) in 1996 and was analysed for anions and cations as described above. Inorganic P was analysed using uv/vis spectroscopy. The paddocks were rotationally grazed by cattle. The soil was a Fleming silt loam which is a naturally poorly-drained sedimentary soil. DRC No. 2 dairy, Hamilton Cation and anion losses were measured in 1995 and 1996 in a farmlet at the DRC No. 2 dairy near Hamilton which received no N fertiliser. Soil solution at 1 metre depth was collected using 30 ceramic cup collectors at 2-3 weekly intervals (Ledgard et al., 1996). The soil was a free-draining Silverdale silt loam (mottled orthic brown soil). Cations and anions in leachate were measured as above. Farmlets receiving nitrogen fertiliser DRC No. 2 dairy, Hamilton Measurements were made of anion and cation leaching in farmlets at the DRC No. 2 dairy near Hamilton. Treatments received 0, 200 or 400 kg N/ha/year as urea in 8-10 split applications throughout the year (Table 1). Table 1: Nitrogen fertiliser applied as urea to farmlets at DRC No. 2 dairy Hamilton (Penno et al., 1996). Leachate from the free-draining Silverdale silt loam (mottled orthic brown soil) was collected using ceramic cup samplers located at 1 metre depth (30 samplers per treatment). Groundwater was also sampled using piezometers (3 per treatment; to a depth of 6 m) located within grazed paddocks of each treatment. The solutions were analysed as above for cations and anions. Phosphate in groundwater was also analysed. The extent of water drainage from each treatment was measured using lysimeters (0.4 m diameter by 1 m deep) containing undisturbed soil cores. The nutrient inputs via fertiliser and rainfall (which were measured) are summarised in Table 2. Fertiliser inputs were muriate of potash applied at 100 kg/ha/year and superphosphate applied at 600 kg/ha/year. Lime was applied to the farmlets at commencement of the trial in 1993. Results Farmlets receiving no N fertiliser High losses of calcium, magnesium, sodium, nitrate-N, sulphate-S, and chloride were observed for the farmlets at No. 2 dairy Hamilton, Waikato and Southland (Table 3). There were lower losses of potassium and inorganic P (all < 1 kg Pi/ha). At each site, the annual amounts leached from the grazed pasture receiving no N fertiliser were in the order Ca > Na > Mg > K and for the anions were in the order Cl > sulphate-S > nitrate-N. At No. 2 dairy, the amounts leached were higher in 1996 than 1995, which coincided with greater drainage. The amounts of calcium and nitrate-N leaching increased ( p< .001) with increasing rate of N fertiliser application at DRC No. 2 dairy during 1996 (Fig. 1). However, there was no effect of N

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Hamilton-based Soil Scientist Dr Gordon Rajendram (PhD) launches his new website on Friday.

Looking for independent soil advice? Then look no further than New Zealand’s leading expert in soil fertility, soil scientist Gordon Rajendram (PhD) on his new website which will be launched on Friday. “This website has been a long time coming and I am excited to finally share it,” says  Soil Scientist Dr Gordon Rajendram. Gordon is New Zealand’s premier agricultural consultant, with more than 35 years of experience in analytical testing development, applied research and consulting to farmers and fertiliser companies. On the website, you can discover how Gordon Rajendram (PhD) can help your farm get the correct soil and mineral balance that grows healthy pasture, crops and animals.  “I am dedicated to helping farmers, so they can get the most out of their soil, so their farm can work more efficiency and sustainability while improving the profitability,” says Gordon. Helping to demystifying the science around soil, Gordon’s new website can start you on your journey to discovering out what elements are needed in your soil. Knowing what elements are needed, helps to stop farmers from applying excessive amounts of fertilisers and reduces the potential environmental damage it may cause. The website also highlights the importance of getting your soil tested and why you needed it done regularly. “Soil testing can help you more effectively use plant nutrients and reduce the leaching or runoff into waterways,” adds Gordon. You can discover more benefits by heading over to the website.

Hamilton-based Soil Scientist Dr Gordon Rajendram (PhD) launches his new website on Friday. Read More »

Dr. Gordon Rajendram Achievements and Awards

With BSc, MSc and a PhD to his name, Gordon is one of the leading experts on laboratory measurement techniques for chemical, biological and physical properties in materials. With a comprehensive and wide-ranging knowledge of IANZ quality systems and procedures in order to have a laboratory, and its testing methods IANZ accredited, Gordon has over twenty six years’ experience in the laboratory, field and research expertise. This is just one of the myriads of reasons on why Gordon is considered one New Zealand’s leading Soil fertility experts. Gordon is a member of New Zealand Society of Soil Science and is also a member of New Zealand Grasslands Society. Gordon has been nominated by AgResearch for Kudos Awards: Scientist of the Year in 2008 for work done on the soil sulphur test and its agronomic advice. He was also nominated by Ministry of Science and Innovation for Kudos Awards: Science Entrepreneur of the Year in 2010 for his work done on precision farming. Achievements Gordon has led the way in many areas, and much of his research & development has been applied in the agriculture industry. He has over 70 publications and five patents to his name, most of these were achieved while he worked at MAF and its predecessor AgResearch, Ruakura Research Centre, Hamilton. https://www.agresearch.co.nz/news/ Leaching of Nutrients: In 1998 Gordon helped with the quantification of cations and anions leached from NZ dairy pastures in a 5-year study carried out in Waikato, Taranaki, and Southland. Because of the significance of this work to New Zealand agriculture the research was incorporated into the Overseer Nutrient model™. https://www.overseer.org.nz/our-news Rapid Measurement Technique, NIR: In 2002 Gordon was able to show that labile nutrients and physical properties in soil could be accurately predicted using Near-Infrared rapid measurement technology (NIR). NIR is now used routinely for soil measurement in NZ. Soil Sulphur (S) and Field Calibration: During 2006, Gordon work on new soil Sulphur test, ‘Total sulphur’ based on 98% organic-S. A laboratory soil test, using pasture field calibration and agronomic advice. This was incorporated into Overseer Nutrient model™. https://www.overseer.org.nz/our-news Soil Nitrogen (N) and Field Calibration: Then in 2008, Gordon developed a field calibrated pastoral soil N test for New Zealand which would be a benefit to NZ agriculture in a massive way. It is the strategic use of N fertiliser on areas of farm based on the N status (Organic –N & the easily mineralised N fraction) of the soil. This IP was brought by Ballance Agri nutrients as part of an $18 Million funding deal with MSI and AgResearch. It was initially called ‘N Guru’ but now has been renamed as ‘Pasture planner’. https://ballance.co.nz/ Phosphate (P) Loss from Agricultural soils: Research project which identifies soils which are at risk of losing P from soil into drainage waters. It is the loss of P from soils, rather than N which poses the greatest risk to water quality and eutrophication. Read more… Nitrogen fertiliser trial database: a valuable resource. Climatic factors and first cut response to nitrogen application. …Read more… EFFECT OF RATE OF NITROGEN FERTILISER ON CATION AND ANION LEACHING UNDER INTENSIVELY GRAZED DAIRY PASTURE…Read more

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Discover what’s going on with your farm nutrients with Hamilton-based Soil Scientist Gordon Rajendram (PhD).

“While you might be feeding 10 stock units per hectare (su/ha) above ground, you need to feed the equivalent of 250 su/ha beneath it,” says Eurofins expert soil scientist, Hamilton based Dr Gordon Rajendram, talking about the multitudes of soil microbes essential to soil, plant and animal health. Rajendram said 13 elements were needed for plant growth, not just nitrogen (N), phosphorus (P) and potassium (K). A further three elements (cobalt, selenium and iodine) were essential for animal health and nutrition. Gordon has been hard at work advocating for the use of fine-grind nutrients blended in suspension as the most effective way to deliver the right elements in the right quantities. “The importance of soil and herbage testing can’t be overstated. At less than 1 percent of your total fertiliser costs, it is a cost-effective investment,” advises Gordon. All tests give you information but some tests which are not tested correctly and regularly are anion storage capacity, or ASC (the P & S retention test), cation exchange capacity (estimates soil’s ability attract, retain and exchange cation elements) and base saturation, which measures the ratio of four key nutrients (cations) to each other. “P used to be the main focus for New Zealand soil fertility, but that has changed. N is now seen as the most limiting nutrient – in combination with soil temperature and moisture,” adds Gordon. “What farmers don’t realise is that, there is a lot happening below ground. Soil leaching, which in general can take away $160 worth of nutrients per hectare per year, mainly happens between April and October,” says Gordon. So, it’s easy to see the importance of soil and herbage tests to see what is going on. Gordon also gave the example of a Northland farm that actually had a very low ASC value but was nonetheless applying heavy doses of soluble P. “Most of it was going straight out to sea. Once we did the testing for them we saved them hundreds of thousands in wasted fertiliser,” comments Gordon. Lastly, Gordon also describes that “dairy farms probably need only about 13kg/ha of P per year, but more than 70kg/ha is sometimes applied, leading to big wastage. Likewise, a farm applying 400kg/ha of N may be losing a quarter of that through leaching, at a cost of more than $100 a hectare.” Credit to Phil Stewart, Deer Industry News Editor, Deer Industry News, August/September 2019, Page 21. Contact Gordon: Email: rajendram@xtra.co.nz Facebook: https://www.facebook.com/Gordon-Rajendram-Soil-Scientist-830978353759572/ Contact MediaPA: Phone: 0274 587 724 Email: phillip@mediapa.co.nz Website: www.mediapa.co.nz Facebook: www.facebook.com/MediaPA Twitter: twitter.com/NZ_MediaPA YouTube: www.youtube.com/user/TheMediaPA Pinterest: www.pinterest.com/NZMediaPA

Discover what’s going on with your farm nutrients with Hamilton-based Soil Scientist Gordon Rajendram (PhD). Read More »

Benefits of testing your soil with New Zealand’s leading expert in soil fertility, Hamilton-based Soil Scientist Dr Gordon Rajendram (PhD).

Defining the pH and fertility level through expert soil testing is the first vital part in planning a nutrient management program that works for you and your farm says New Zealand’s leading expert in soil fertility, Hamilton-based Soil Scientist Dr Gordon Rajendram (PhD). “Testing and sampling is the most crucial step in the process of nutrient management,” says Soil Scientist Dr Gordon Rajendram. Spreading fertiliser on your soil without knowing the exact nutrient balance needed will lead to over-fertilisation. Testing your soil, pasture or herbage, and specific plants such as clover, prior to fertilisation, finds out what elements are needed. This, therefore, prevents farmers from applying excessive amounts of fertilisers and reduces the potential environmental damage it may cause. Having efficient and professional testing done has myriad of benefits that help farmers get the most out of their farm while keeping the environment healthy. One of the more prominent benefits, is that it can help improved yields and profitability from providing needed nutrients for the crop. “Healthy soil improves crop growth,” adds Gordon. It can also give you more uniform crop growth, which makes individual plants more competitive with weeds, which in turn will help ease other management practices such as spraying, simplifying crop harvesting and drying and improving market quality. Soil sampling and testing can also help reduce your environmental impact. Continuous cultivation for instance can ‘wear out the land’ on which you grow your crops and feed your animals. Soil testing can help you more effectively use plant nutrients and reduce the leaching or runoff into waterways. “Not only that but, poorly nourished crops will have minimal plant residue to hold soil in place, which saves it from wind and water erosion,” adds Gordon. Regular soil testing, combined with a thorough record-keeping system for each field can serve as a scale to indicate whether soil fertility is increasing, decreasing, or remaining constant.  Soil fertility on many farms may be declining due to poor or deficient nutrient management. Check out Gordon’s latest video here: https://www.facebook.com/GordonRajendramSoilScientist/videos/2672626519515200 Contact Gordon: Email: rajendram@xtra.co.nz Facebook: https://www.facebook.com/GordonRajendramSoilScientist Contact MediaPA: Phone: 0274 587 724 Email: phillip@mediapa.co.nz Website: www.mediapa.co.nz Facebook: www.facebook.com/MediaPA Twitter: twitter.com/NZ_MediaPA YouTube: www.youtube.com/user/TheMediaPA Pinterest: www.pinterest.com/NZMediaPA

Benefits of testing your soil with New Zealand’s leading expert in soil fertility, Hamilton-based Soil Scientist Dr Gordon Rajendram (PhD). Read More »

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