Afrikaans: Stikstofbemesting vir Intensiewe Weidingproduksie Nitrogen (N) is the nutrient taken up in largest quantities by pasture plants from the soil. Its availability, together with temperature and moisture supply, are usually the major factors determining the productivity of pastures. Responses of grasses to applied N The responses of pastures to fertilizer N have been studied in scores of research trials both locally and overseas. In South African research, the major focus has been on the N requirements of ryegrasses, kikuyu and Eragrostis curvula (weeping lovegrass), with limited work being carried out on other species such as cocksfoot, fescue and Digitaria eriantha (Smuts fingergrass). For the relation between grass DM (dry matter) yield and fertilizer N applied, a characteristic response curve is obtained, an example of which is presented in Figure 1. When N is applied there is usually an initial near-linear response (A in Fig. 1), a phase of sharply diminishing response (B) and a point (C) beyond which N has little or no effect on yield. The amount of DM produced for each kilogram of N applied within zone A depends largely on the species under consideration, the frequency of defoliation and growth conditions. Tropical grasses generally produce more DM per unit of N than do temperate grasses. In field trials, Eragrostis curvula, for example, has produced up to 60 kg DM per kg N applied, but irrigated Italian ryegrass only between 25 and 34 kg DM per kg N applied. In the United Kingdom, perennial ryegrass produced an average of 23 kg DM/kg N over an N application range of 0 – 300 kg N/ha. It must be emphasised that data such as these are averages over the season and conceal wide variations in response efficiency within the season. For example, in perennial ryegrass the spring response is two to three times greater than at other times of the year. Milk production response On intensive dairy pastures, the additional feed produced in response to N fertilization is ideally converted into milk production. A typical conversion ratio is about 15 kg pasture dry matter per kg milk-solids, or roughly one kg pasture dry matter per liter of milk. In South Africa currently, the value of pasture dry matter in dairy farm operations is estimated to be approximately R2000/ton. In overseas studies, it has been estimated that the response in terms of milk production ranges from 9 to about 16 kg milk per kg fertilizer N applied. This arises not because of any significant increase in yield per cow, but from an increase in stocking rate, i.e. cows per hectare. Type of fertilizer Urea and LAN (limestone ammonium nitrate) are the two most important forms of fertilizer N used on pastures, with other products such as ammonium sulphate being used in lesser amounts. Grasses take up N in both the ammonium and nitrate forms; however, since ammonium (including the N in urea) is converted to nitrate within a few weeks in well-aerated non-acidic soils at temperatures above about 5˚C, most of…
Book your place for the annual No-Till Conference to held on from 3 – 5 September 2019 at the ATKV Drakensville Holliday Resort, Drakensville, Kwa Zulu Natal. The theme for this years conference is The Regeneration of Agriculture Responsibly – by adopting The No-Till CA System. Bill Crabtree from the Australia is this years international guest speaker and will discuss “Why is residue so important?– biologically, chemically and physically”, ” What are the best crop rotations?” and ” Soil Chemical Fertility Restraints”. This conference provides a comprehensive program, some of the speakers include Prof Charlie Reinhardt discussing “The controversy around glyphosate – how much based on facts and how much based on perceptions?”; Dr Philip Theunissen speaking on “Should soil conservation be on your balance sheet?” and Deon Schroder discussing “Sugarcane farming: Changing a paradigm” 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 “Head, Heart And Guts – Examples from the World”. Take advantage of the Early Bird Registration which lasts until 26 August 2019 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 Conference Programme: http://www.notillclub.com/images/2019 NO-TILL CONFERENCE PROGRAMME.pdf Registration forms: 2019 Delegates Registration
Book your place for the FERTASA Soil Fertility and Plant Nutrition Symposium to held on 21 & 22 August 2019 at the CSIR International Convention Centre, Pretoria. The symposium theme is “Back to Basics for the Future”. Some of the guest speakers include Prof Jude Odhiambo covering Soil Origin and Variability; Chris Gazey from Australia covering Regenerative Agriculture; Prof Leon van Rensburg covering Physical Soil Properties: Electro Magnetic Induction; Dr Johan van Biljon covering Plant Nutrition: Principles of Fertilization and Pius Floris from Plant Health Cure, Netherlands, covering the Difference Between Soil Biology & Root Biology Full Symposium Programme: http://www.fertasa.co.za/wp-content/uploads/2019/07/Final-Programme_Day1and-2-2019-Symposium.pdf Individual Registration: https://gallery.mailchimp.com/82ec9305f615ca6c7de03c7d5/files/d45f6fea-f506-4ec5-8e04-6d2a6494c441/INDIVIDUAL_Registration_Form_2019.01.pdf
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Dr Neil Miles consulting soil scientist
Neil Miles is a consulting soil scientist based in Mount Edgecombe. Prior to entering into consultancy, he spent 28 years with the KZN Department of Agriculture, as a research scientist and research manager, followed by 10 years in research and advisory work with the South African Sugarcane Research Institute (SASRI).
Neil played a leading role in the development of both the Cedara Fertilizer Advisory Service and SASRI’s Fertiliser Advisory Service (FAS). His PhD, through the University of Natal, focused on the nutrition of intensive pastures. Neil’s particular interests are soil health and the nutrition of crops and pastures.
Contact Neil: firstname.lastname@example.org