AFRIKAANS: El Nino of La Nina – bestuur stikstof (N) in die grond om maksimum mielieopbrengs, maksimum wins en minimum risiko te verseker The quantity of measurable inorganic N that should be in the soil throughout the growing period for maximum yield does not differ between El Nino (dry) or La Nina (wet) or average rainfall seasons but the actual yield, profitability and risk will differ to a large extent between these conditions. The quantity of N that is taken up and utilized by the crop will also differ largely between dry and wet seasons. For this reason it can be expected that more N will be applied during a wet season to maintain the quantity of N in the soil. It can also be expected that more N will be left over in the soil after a dry season which can effectively be utilized during the next season. The management of a threshold value for N in the soil for every season will effectively result in fertilization according to obtained yield and N removal from the soil over seasons. N-losses and N-toxicity effects will however very strongly be affected by an under or over supply of rain. Apart from soil N-measurements, choice of N-source and N-management practices can effectively be used to reduce these negative effects. El Nino conditions also coincide with high temperatures resulting in volatilization losses from ammonia forming products such as urea. Ammonia losses can result from surface applications as well as soil incorporated applications when the topsoil dries out. Ammonia released in close proximity of plant roots will be toxic under dry conditions. Urease inhibitors such as NBPT will effectively reduce or delay volatilization and toxicity from urea but will not eliminate these effects. Almost no N will volatilize from LAN even at high temperatures. LAN will only be moderately toxic at high concentrations. The band placement of high concentrations ammonia forming N-sources at planting but even before plating should therefore be avoided. La Nina conditions also coincides with heavy downpours over short periods resulting in N-leaching in well drain soils or water logging in poorly drained soils. Urea-N and nitrate-N are equally leachable but due to the fact that nitrate uptake is much quicker it will effectively leach much less than urea. Ammonium-N does not leach significantly and is also taken up much quicker than urea-N. LAN will therefore also leach much less than urea. Due to the possible risk of leaching pre-plant applications should rather be avoided and multiple post-plant topdressings considered. N is not taken up effectively in soils that are waterlogged for prolonged periods. Oxygen is required for N-uptake but also for the nitrification process. Consequently high levels of ammonium-N and nitrite-N, which are toxic, will accumulate. Nitrate-N dissolved in soil water near the soil surface will be converted to atmospheric N through the denitrification process and lost. Vertical or lateral drainage of soils should improve this condition.
Book your place for the annual No-Till Conference to held on from 4 – 6 September 2018 at the ATKV Drakensville Holliday Resort, Drakensville, Kwa Zulu Natal. The theme for this years conference is Managing Adversity with Diversity with Emerging Cover Crop Strategies by Making Cover Crops Pay. Steve Groff from the USA is this years international guest speaker and will conduct an in depth Cover Crop and Soil Fertility workshop discussing “Tips for Making Cover Crops Work in Dryland Areas”, ” Taking Cover Crops to the Next Level” and “Bringing Animals Back to the Land”. This conference provides a comprehensive program, some of the speakers include soil scientist Guy Thibaud covering “Restoration of previously degraded soils is a key factor in the transition to No-Till” Simon Hodgson on “using cover crops and plants to advance biological control of insects” and Dr Colin Forbes on “Moving to No-Till on a mixed farming operation” I you have an interest in Conservation Agriculture and improving the productivity of your soil, this conference provides and excellent opportunity to meet research scientists and farmers who will share their experiences and learnings on how to successfully reap the benefits of No-Till farming. Motivational speaker Quinton Coetzee will address the delegates on Wednesday evening on “THRIVING IN TOUGH TIMES – Lessons from the Wild”. Take advantage of the Early Bird Registration which lasts until 24 August 2018 to avoid the late registration fee. For more information on the principles and practice of no-till farming and the No-Till club visit: www.notillclub.com 2018 NO-TILL CONFERENCE PROGRAMME 2018 BEWARINGSLANDBOUKONFERENSIE PROGRAM 2018 Delegates Registration Form 2018 Contact Numbers For Accommodation