MPCN II Southern Region Farmer Case Study Nutrient test strips in the paddock follow research talk at the Hart Field-Site in South Australia. Author: Louisa Ferrier, Project Manager, BCG Contributors: Dr. Kate Burke, Think Agri Consulting, Dr. Sean Mason, Research Agronomist - Director Agronomy Solutions, Dr. Sarah Noack, Research and Extension Manager, Hart Field-Site Group. extensionhub, 2017 This publication is copyright. Except as permitted under the Copyright Act 1968 (Commonwealth), no part of the publication may be reproduced by any process, electronic or otherwise, without the specific written permission of the copyright owner. Neither may information be stored electronically in any form whatever without such permission. More Profit from Crop Nutrition
Name: Justin Wundke Location: Condowie, South Australia Sarah Noack, Hart Field-Site Group research and extension manager and Justin Wundke, Condowie Farmer. Soil type: Calcareous loam and a small amount of deep sand Farm system: Direct drill, press wheel, knife point Average annual rainfall: 330mm, 250mm growing season Justin Wundke farms in the mid-north of South Australia, with his wife Beck, parents Dennis and Karen, and brother Bradley. They run a cropping and prime lamb sheep enterprise with the majority (approximately 90 per cent) being cropping including wheat, barley, oaten hay and legumes. The Wundkes recently leased some sandier country which is different to the calcareous loams they are used to. We sowed Compass barley onto the sandy soil this year and were keen to get the nutrition on the new land right, Justin said. I knew it was a soil type likely to run into a sulphur deficiency. It was coincidental that at a local Hart crop walk research agronomist Dr Sean Mason (Agronomy Solutions) was presenting on crop nutrition. 2 MPCN II Southern Region Farmer Case Study
Predicting a crop response to sulphur Justin joined seventy other farmers at a potassium (K) and sulphur (S) response trial at Hart s field research site where Dr Mason emphasised that a sound soil monitoring program was the starting point to identify potential nutrient deficiencies. While soil tests can often suggest more (S) and K should be applied, a response to fertiliser application is not always observed and this can relate to the depth of the soil sample, he said. Some of the recent GRDC work we have been involved in (GRDC project number UA00140) suggests critical soil test levels for S can be the first point of inaccuracy and need to be refined for different soil types associated with the southern cropping region. Current critical value recommendations for S (KCl-40 soil test) were established at 4.5mg/kg for wheat and 6.8mg/kg for canola at 0-10cm from research summarised by Anderson et al. (2013) in Western Australia. However, research in south eastern Australia failed to observe similar findings. The research looked at identifying critical values in a number of soil types from western, southern and northern growing regions of Australia in a glasshouse environment at Zadok s cereal growth stage 30 in wheat and at the vegetative stage in canola. This research found critical values were 2.6mg/kg for wheat and 2mg/kg for canola which are much lower than the Western Australian values. These lower critical values have been supported by recent field trial work in South-eastern Australia where responses to S applications have been difficult to achieve at soil test levels around 3mg/kg (GRDC project number DAN00168). Dr Mason said nutrient stratification can also be an issue when trying to identify if S or K is limiting. S is quite mobile in soil and can move away from the surface soil layer where it is applied, he said. Therefore farmers need to sample deeper than a traditional 0-10 cm soil test. Sulphur levels in soil are relatively easy to address because most soil types have a limited ability to lock up S. Additionally, S is inadvertently supplied through gypsum, sulphate of ammonia and small amounts via MAP and DAP fertiliser applications. Crop nutrition researcher Sean Mason speaking to growers at the Hart Field-Site in South Australia. 3 MPCN II Southern Region Farmer Case Study
On-farm trial At the crop walk Justin had noted that each product would test a different response: gypsum provides S only; urea would show a response to N; and sulphate of ammonia contains both S and N. Armed with this knowledge, Justin went home and set up his own test strip S trial in his Compass barley crop. It was pretty basic, but I set up a trial with four fertiliser treatments, including an untreated, and I hand spread sulphate of ammonia, urea and gypsum when the crop was at Zadok s cereal growth stage 31 (end of tillering), he said. In a matter of weeks, Justin observed a greening of the crop in response to the three fertiliser treatments. It seemed likely that the crop was responsive to N as well as S, he said. The results will be validated at harvest by assessing any changes in yield. Sulphur is important in the formation of chlorophyll and plants display a lighter green canopy colour in response to low S, similar to N deficiency. The difference with S deficiency is that since it is relatively immobile once in the plant, deficiency symptoms are more pronounced in the youngest foliage. These observations have already prompted a change in the Wundke s soil testing for next year. We are planning on conducting deep soil testing (0-60 cm) in autumn, followed by more test strips to ground-truth the concept and maybe some tissue testing in-season, Justin said. 4 MPCN II Southern Region Farmer Case Study
Phosphorus The response of wheat and barley varieties to phosphorus (P) was another feature of Dr Mason s session at the Hart crop walk. He shared the results of recent work with the South Australian Grain Industry Trust (GRDC project numbers UA1115 and UA2101) which has been investigating whether new varieties are more efficient at accessing P sources and therefore have differing requirements for P. According to Dr Mason, the main outcome so far has been that the benefit of increased yields through the most suitable choice of varieties outweighs any differences between P use efficiency of the varieties. To date, we haven t been able to identify significant differences between varieties and their external P requirements, he said. This project identified P as a major limitation to crop yields on soil types which tend to have a moderate to high ability to fix applied P. Commonly, these soils have a high PBI (phosphorous buffering index), usually above 80. One of the trials sites established as part of this project was near Condowie and on a similar soil type to that on the Wundke s property. Dr Mason said that after periods of cutting back P inputs, these soil types can test low in P. He said in some soil types with very high PBI values, research has shown economic responses to P rates ranging from 15 to 30 kg P/ ha. The key message is to test for PBI as well as Colwell P if you think you have a potentially high P fixing soil and if the high PBI is driven by carbonate then DGT is a more suitable test, Dr Mason said. With this in mind, Justin said he planned on establishing some P rich strips at seeding next year. Condowie soils may have economic returns up to 30kg P/ha, he said. We were aware some of our soil lock up a lot of P, but to see the economics helps us make more informed decisions. Dr Mason encouraged Justin to back up his fertiliser strips with yield data and soil testing. MCPN II southern extension project coordinator Louisa Ferrier said the learnings from research projects such as Dr Mason s and others in the initiative can lead to practical and profitable strategies for growers. It is important to get the basics right, she said. 5 MPCN II Southern Region Farmer Case Study
The take home messages Soil sampling depth of 0-10 cm is adequate for P but conduct soil tests to depth for a more accurate indication of the N, S and K status of your soils. Ideally sampling depth should capture the root zone and this will vary according to the crop type and soil type. Deep soil N testing (for example 0-10, 10-60 cm) is a wellestablished practice. Including K and S when conducting deep soil tests will provide better value for your testing dollar. If you are testing for P, make sure you get Colwell P and PBI and also DGT if the option is offered. Use paddock strip trials to validate your soil tests and assess the most cost effective rate of fertiliser for your crop. Ideally trials should contain a control (0 rate), standard rate (replacement) and a P rich strip (2-3 x replacement) and always validate with harvest yield results. Try to ensure N is non-limiting so any crop response can be associated with P and not N. BCG is carrying out extension in the southern region as part of the GRDC More Profit from Crop Nutrition II initiative (MPCN). The project, BWD00021 Extension and training (southern region), focuses on equipping growers and advisors to make more dollars from their fertiliser budgets. The BCG team pools information from well renowned soil and crop nutrition specialists and the suite of the MPCN projects to deliver events to growers across the region. For further information on the project contact Louisa Ferrier (BCG) on 03 5492 2787. Useful Resources Making Better Fertiliser decisions for Cropping Systems in Australia: http://www.bfdc.com.au/interrogator/frontpage.vm Soil Testing for Crop Nutrition (Southern Region) www.grdc.com.au/grdc-fs-soiltestings UA00103 - DGT as the soil test of choice for predicting phosphorus requirements of grain crops http://finalreports.grdc. com.au/ua00103 DGT factsheet: http://soilquality.org.au/factsheets/dgtphosphorus Is there a preferred wheat or barley variety to grow in a P deficient soil? http://www.msfp.org.au/preferred-wheat-barley-varietygrow-p-deficient-soil References Anderson, GC, Peverill, KI, Brennan, RF (2013) Soil Sulfur Crop response calibration relationships and criteria for field crops grown in Australia, Crop and Pasture Science 64: 514 522. Doi: http://dx.doi.org/10.1071/cp13006 Mason, S, and Armstrong, R (2016) Monitoring of soil phosphorus, potassium and sulphur in the southern region how to get the most out of your fertiliser dollar, 2016 Bendigo GRDC Grains Research Update. Pp 169 173. More Profit from Crop Nutrition 6 MPCN II Southern Region Farmer Case Study