{"id":23,"date":"2018-09-07T04:00:35","date_gmt":"2018-09-07T04:00:35","guid":{"rendered":"http:\/\/agrispex.co.za.dedi30.cpt1.host-h.net\/?p=23"},"modified":"2019-11-19T14:32:52","modified_gmt":"2019-11-19T14:32:52","slug":"","status":"publish","type":"post","link":"https:\/\/agrispex.co.za\/fr\/differences-in-toxicity-effects-between-lan-and-urea\/","title":{"rendered":"","raw":""},"content":{"rendered":"","protected":false,"raw":""},"excerpt":{"rendered":"AFRIKAANS:\u00a0Die verskil in toksisiteit tussen KAN en ureum Dr Erik Adriaanse Plant mixtures differ to a large extent in nitrogen (N) composition. Nitrate-N: ammonium-N ratios vary according to raw material contents. The optimum nitrate: ammonium-ratio is close to 3:1 while 100% ammonium-N could impair plant growth and yield (Adriaanse 1990). Some companies use urea-N as the primary N source in plant mixtures. Urea in\u00a0close proximity\u00a0to developing seedlings could impair or terminate growth. The band placement of certain N sources away from the plant mixture could also reduce yield. (Adriaanse 2012). Furthermore yield could be reduced by an overall excess of N in the soil. (Adriaanse and Schmidt, 2003). This article focuses on potential negative effects of band placed LAN and urea on germination, emergence, and production of maize and wheat. Plant Population Reductions The application of urea and ammonium nitrate at the same relatively high N rate may result in high\u00a0seedling mortalities for urea compared to no mortalities for ammonium nitrate (Figure 1). These symptoms are often mistaken for genetically associated poor germination or poor seedling vigour. In addition these symptoms are often wrongly ascribed to damage caused by soil insects or meerkats. Figure 1: The effect of relatively high concentrations of urea and ammonium nitrate at the same N concentration on germination and emergence of maize seedlings. (Yara, 2008) Figure 2. Effect of increasing rates of Urea and LAN on the reduction of maize plant population. N Sources were band placed 50 to 100 mm below the seed. Row widths were 1.5 m. Clay content in the top 15 cm soil was 9.1%. (Adriaanse, 1991 The band placement of 100 kg N\/ha, 50 to 100 mm directly below maize seed at row widths of 1.5 m, resulted in a plant population loss of 4800 plants\/ha with LAN compared to a loss of 13300 plants\/ha when urea was used (Figure 2). Reductions in plant population were significantly more with urea compared to LAN at both 75\u00a0and 100 kg N\/ha (Figure 2). This research illustrates relative differences in toxicity between urea and LAN under\u00a0very specific conditions but does not imply that band placement of either of these N sources directly below the seed at low N rates is an acceptable practice under all conditions. Yield Loss Reductions in plant population due to the application of high N rates, is an indication of very severe N toxicity effects. Impairment of plant growth and yield loss could occur at much lower N concentrations. In another study where urea and LAN were band placed at planting, at a distance of 10 to 15 cm from the row, at a depth of 10 cm, the yield loss for urea compared to LAN was 20% at 100 kg\/ha and 44% at 175 kg\/ha (Adriaanse, 2012). Row widths were 1.5 m. Most farmers would probably not have been aware of the fact that urea toxicity had occurred.\u00a0 The yield at 100 kg N\/ha in the form of urea was 5 ton\/ha which is in line with the...","protected":false,"raw":""},"author":15,"featured_media":1296,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_en_post_content":"AFRIKAANS:\u00a0Die verskil in toksisiteit tussen KAN en ureum<\/strong><\/a>\r\n\r\n[caption id=\"attachment_1270\" align=\"alignright\" width=\"150\"]\"\"<\/a> Dr Erik Adriaanse[\/caption]\r\n\r\nPlant mixtures differ to a large extent in nitrogen (N) composition. Nitrate-N: ammonium-N ratios vary according to raw material contents. The optimum nitrate: ammonium-ratio is close to 3:1 while 100% ammonium-N could impair plant growth and yield (Adriaanse 1990). Some companies use urea-N as the primary N source in plant mixtures. Urea in\u00a0close proximity\u00a0to developing seedlings could impair or terminate growth. The band placement of certain N sources away from the plant mixture could also reduce yield. (Adriaanse 2012). Furthermore yield could be reduced by an overall excess of N in the soil. (Adriaanse and Schmidt, 2003). This article focuses on potential negative effects of band placed LAN and urea on germination, emergence, and production of maize and wheat.\r\n\r\nPlant Population Reductions<\/strong>\r\nThe application of urea and ammonium nitrate at the same relatively high N rate may result in high\u00a0seedling mortalities for urea compared to no mortalities for ammonium nitrate (Figure 1). These symptoms are often mistaken for genetically associated poor germination or poor seedling vigour. In addition these symptoms are often wrongly ascribed to damage caused by soil insects or meerkats.\r\n\r\n[caption id=\"attachment_1285\" align=\"aligncenter\" width=\"560\"]\"\"<\/a> Figure 1: The effect of relatively high concentrations of urea and ammonium nitrate at the same N concentration on germination and emergence of maize seedlings. (Yara, 2008)[\/caption]\r\n\r\n[caption id=\"attachment_1296\" align=\"aligncenter\" width=\"560\"]\"\"<\/a> Figure 2. Effect of increasing rates of Urea and LAN on the reduction of maize plant population. N Sources were band placed 50 to 100 mm below the seed. Row widths were 1.5 m. Clay content in the top 15 cm soil was 9.1%. (Adriaanse, 1991[\/caption]\r\n\r\nThe band placement of 100 kg N\/ha, 50 to 100 mm directly below maize seed at row widths of 1.5 m, resulted in a plant population loss of 4800 plants\/ha with LAN compared to a loss of 13300 plants\/ha when urea was used (Figure 2). Reductions in plant population were significantly more with urea compared to LAN at both 75\u00a0and 100 kg N\/ha (Figure 2). This research illustrates relative differences in toxicity between urea and LAN under\u00a0very specific conditions but does not imply that band placement of either of these N sources directly below the seed at low N rates is an acceptable practice under all conditions.\r\n\r\nYield Loss<\/strong>\r\nReductions in plant population due to the application of high N rates, is an indication of very severe N toxicity effects. Impairment of plant growth and yield loss could occur at much lower N concentrations. In another study where urea and LAN were band placed at planting, at a distance of 10 to 15 cm from the row, at a depth of 10 cm, the yield loss for urea compared to LAN was 20% at 100 kg\/ha and 44% at 175 kg\/ha (Adriaanse, 2012). Row widths were 1.5 m. Most farmers would probably not have been aware of the fact that urea toxicity had occurred.\u00a0 The yield at 100 kg N\/ha in the form of urea was 5 ton\/ha which is in line with the yield potential of the area. No toxicity symptoms were observed on the plants, however a yield improvement of 20% at 100 kg N\/ha could have been achieved had LAN been used under the same circumstances.\r\n\r\nToxicity Symptoms<\/strong>\r\nToxicity symptoms associated with high rates of both urea and LAN applications would probably result in yield loss due to high N concentrations in the soil. In contrast, scorching of leaves associated with spreading of N sources over leaf canopies would probably not result in yield loss. Typical symptoms resulting from high N concentrations in the soil are necrotic leaf tips and edges on the youngest leaves. (Figure 3 and Figure 4). Scorching of leaves due to spreading of fertilisers over leaves show some similarities but lesions in areas where fertilisers were in direct contact with leaves would also be visible. Scorching symptoms resulting from urea spreading (Figure 5) is often less prominent than symptoms associated with LAN spreading (Figure 6) but neither of the two, as was previously stated, is expected to result in yield losses.\r\n\r\n[caption id=\"attachment_1289\" align=\"aligncenter\" width=\"560\"]\"\"<\/a> Figure 3. Urea toxicity symptoms on leaf tips of wheat, due to high concentrations in the soil (Yara, 2008).[\/caption]\r\n\r\n[caption id=\"attachment_1265\" align=\"aligncenter\" width=\"560\"]\"\"<\/a> Figure 4. Urea toxicity symptoms on maize leaf tips and edges due to high concentrations in the soil (Yara 2005)[\/caption]\r\n\r\n[caption id=\"attachment_1266\" align=\"aligncenter\" width=\"552\"]\"\"<\/a> Figure 5. Urea scorching effects after spreading over the leaf canopy (Yara, 2006)[\/caption]\r\n\r\n[caption id=\"attachment_1267\" align=\"aligncenter\" width=\"552\"]\"\"<\/a> Figure 6. LAN scorching effects after spreading over the leaf canopy (Adriaanse 2010)[\/caption]\r\n\r\nConclusions and recommendations<\/strong>\r\n
    \r\n \t
  1. The risk of urea containing plant mixtures impairing germination and seedlings development is much greater compared to LAN based plant mixtures. Reductions in plant populations and retarded growth could result in significant yield losses. Although toxicity effects are strongly affected by climatic conditions it is recommended that urea should rather not be used in plant mixtures intended for band placement.<\/li>\r\n \t
  2. The band placement of urea at planting away from the plant mixture could also result in significant yield loss at relatively high N rates while this effect was not observed with LAN. For this reason it is recommended that urea should rather not be band placed close to plant rows at planting.<\/li>\r\n \t
  3. Farmers should look out for toxicity symptoms such as necrotic leaf tips and leaf edges surrounding leaf tips. These symptoms may result from high urea-N concentrations or from general oversupply of N to the soil. Significant yield losses could be expected to follow these symptoms. In contrast the scorching of leaves due to the spreading of either LAN or urea over leaves is not expected to result in yield losses.<\/li>\r\n<\/ol>\r\nNB. Consult a qualified agronomist for locality specific applications. The results referred to in this article were obtained under specific conditions and are therefore not generally applicable under all conditions.<\/strong><\/em>\r\n
    References:<\/strong>\r\nADRIAANSE F.G., 1990. Effects of nitrate: ammonium ratios, times of application and prolificacy on nitrogen response of Zea mays L. Ph. D. University of the Free State.\r\nADRIAANSE F. G. 1991. Unpublished research report on nitrogen placement, ARC-GCI, Potchefstroom.\r\nADRIAANSE, F. G., 2012. KAN of ureum: voor-plant, met-plant of na-plant. S A Graan\/Grain 05\/12.<\/h6>\r\n
    ADRIAANSE, F. G. & SCHMIDT. 2003. N-aanbevelings volgens N-ontledings in\r\ndie grond \u2013 die enigste antwoord. S A Graan\/Grain. 7\/03.<\/h6>\r\n ","_en_post_name":"differences-in-toxicity-effects-between-lan-and-urea","_en_post_excerpt":"","_en_post_title":"Differences in toxicity effects between LAN and urea","_af_post_content":"[caption id=\"attachment_1270\" align=\"alignright\" width=\"150\"]\"\"<\/a> Dr Erik Adriaanse[\/caption]\r\n\r\nENGLISH:\u00a0Differences in toxicity effects between LAN and urea<\/strong><\/a>\r\n\r\nPlantmengsels verskil wat stikstof (N) samestelling aanbetref. Die nitraat-N: ammonium-N-verhouding kan in \u2018n groot mate verskil afhangende van die verhouding van grondstowwe wat gebruik is. Die optimum nitraat: ammonium-verhouding is naby 3:1 terwyl 100% ammonium wat gebandplaas word gewoonlik plantegroei en opbrengs onderdruk (Adriaanse 1990). Sommige verskaffers gebruik gedeeltelik of uitsluitlik ureum-N in plantmengsels. Ureum naby ontwikkelende saailinge kan in so \u2018n mate toksies wees dat ontkiemende saad en saailinge afsterf. Die bandplasing van sekere stikstofbronne naby ontwikkelende saailinge weg van die plantmengsel kan ook opbrengs onderdruk (Adriaanse 2012). Verder kan gewasproduksie onderdruk word wanneer N algeheel oorvoorsien is (Adriaanse & Schmidt, 2003) . Hierdie artikel fokus veral op moontlike nadelige effekte en simptome van gebandplaasde KAN en ureum op ontkieming, opkoms en produksie van mielies en koring.\r\n\r\nPlantestandverlies<\/strong>\r\nUreum-N wat die ontkieming en opkoms van saad sodanig inhibeer dat jong saailinge afsterf word in Foto 1 aangetoon. Ammoniumnitraat wat teen dieselfde N konsentrasie toegedien is, het geen toksiese effekte getoon nie (Foto 1). Produsente verwar dikwels di\u00e8 simptome met swak kiemkragtigheid of groeikragtigheid van saad. Verder word sulke swak opkoms onder andere ook verkeerdelik toegeskryf aan die skade wat deur meerkatte of grondinsekte veroorsaak word.\r\n\r\n[caption id=\"attachment_1285\" align=\"aligncenter\" width=\"560\"]\"\"<\/a> Foto 1: Die effek van ho\u00eb konsentrasies ureum en ammoniumnitraat by dieselfde N konsentrasie op ontkieming en opkoms van mielies. (Yara, 2008)[\/caption]\r\n\r\n[caption id=\"attachment_1298\" align=\"aligncenter\" width=\"560\"]\"\"<\/a> Grafiek 1. Die effek van KAN en ureum op plantestandverlies. N-bronne is 50 tot 100 mm onder die saad by ry-wydtes van 1.5 m gebandplaas. Die klei-inhoud was 9.1% in die boonste 15 cm grond (Adriaanse, 1991).[\/caption]\r\n\r\nNavorsing aan die LNR-IGG (Adriaanse,1991) het aangetoon dat die verlies aan plantestand soveel as 5000 plante\/ha met KAN kan wees teenoor nagenoeg 16000 plante\/ha met ureum wanneer hierdie bronne teen 100 kg N\/ha, 50 tot 100 mm direk onder die saad by 1.5 m wye rye gebandplaas is (Grafiek 1). Die plantestandverlies by toedienings van 75 en 100 kg N\/ha was betekenisvol meer met ureum as met KAN (Grafiek 1).\r\n\r\nOpbrengsverlies<\/strong>\r\nPlantestandverlies is \u2018n aanduiding van baie erge toksisiteit. Onderdrukking van plantegroei en opbrengsverlies kan dus by veel laer N-toedienings verwag word. Ureum wat so ver weg as 10 tot 15 cm vanaf rye en 10 cm diep met planttyd geplaas is, het mielieopbrengs onderskeidelik met 20% en 44% by N-peile van 100 kg\/ha en 175 kg\/ha by ry wydtes van 1.5 m teenoor KAN onderdruk (Adriaanse, 2012). Produsente wat ureum op hierdie wyse toegedien het sou in alle waarskynlikheid nie bewus gewees het van die verlies aan opbrengs weens ureum toksisiteit nie. Daar is steeds \u2018n opbrengs van 5 ton\/ha by ureum toedienings van 100 kg N\/ha verkry, wat naby aan die potensiaal vir die gebied is, en geen toksiese simptome is op die plante waargeneem nie.\r\n\r\nSimptome<\/strong>\r\nSimptome van ureum en KAN toksisiteit weens te ho\u00eb konsentrasies in die grond sal heel waarskynlik lei tot opbrengsverlies. Daarteenoor sal toksiese skroei-simptome wat veroorsaak is deur uitstrooiings oor die blaredak, waarskynlik nie aanleiding gee tot opbrengsverlies nie. Simptome van ureum en KAN toksisiteit weens ho\u00eb konsentrasies in die grond vertoon dooie blaarpunte en blaarrante van die voorste dele van nuwe blare (Foto 2 en Foto 3). Skroei-simptome stem ooreen hiermee, maar ander dele van blare wat direk aan die kunsmis blootgestel is sal ook letsels toon. Skroei-simptome wat deur ureum uitstrooiings (Foto 4) veroorsaak is, is gewoonlik nie so erg as wat deur KAN uitstrooiings (Foto 5) veroorsaak is nie, maar soos reeds gestel, nie van enige betekenis wat opbrengsverlies vir enige van die N-bronne aan betref nie.\r\n\r\n[caption id=\"attachment_1264\" align=\"aligncenter\" width=\"552\"]\"\"<\/a> Foto 2. Ureum toksisiteit op die punte van koringblare weens ho\u00eb konsentrasie in die grond (Yara, 2008).[\/caption]\r\n\r\n[caption id=\"attachment_1265\" align=\"aligncenter\" width=\"560\"]\"\"<\/a> Foto 3. Ureum brand op die punte en rante van blare weens ho\u00eb konsentrasies in die grond by mielies (Yara 2005)[\/caption]\r\n\r\n[caption id=\"attachment_1266\" align=\"aligncenter\" width=\"552\"]\"\"<\/a> Foto 4. Ureum skroei na uitstrooiing oor plante (Yara, 2006)[\/caption]\r\n\r\n[caption id=\"attachment_1267\" align=\"aligncenter\" width=\"552\"]\"\"<\/a> Foto 5. KAN skroei na uitstrooiing oor plante (Adriaanse 2010)[\/caption]\r\n\r\nGevolgtrekkings en aanbevelings:<\/strong>\r\n
      \r\n \t
    1. Ureum in plantmengsels wat gebandplaas word, hou \u2018n baie groter gevaar in vir ontkiemende saad en ontwikkelende saailinge as KAN. Plantestandverlies en groeistremming kan lei tot betekenisvolle opbrengsverlies. Hoewel toksiese effekte in \u2018n groot mate van klimaatsomstandighede afhanklik is behoort ureum weens die risiko\u2019s daaraan verbonde nie in plantmengsels gebruik te word nie.<\/li>\r\n \t
    2. Ureum wat met planttyd veel verder weg as plantmengsels gebandplaas word kan teen ho\u00ebr toedienings opbrengs betekenisvol onderdruk terwyl die effek nie by KAN waargeneem is nie. Ureum behoort daarom verkieslik nie met planttyd naby plantrye gebandplaas te word nie.<\/li>\r\n \t
    3. Produsente behoort bedag te wees op tekens van blaarpunte en rante van die voorste gedeeltes van blare wat gebrand is. Hierdie simptome kan deur te veel ureum in die grond of algehele oorvoorsiening van N veroorsaak word. Opbrengsverlies kan heel moontlik die verdere gevolg van die simptoom wees. Simptome van blaarskroei wat onstaan nadat KAN of ureum oor plante uitgestrooi is, moet hiervan onderskei word want dit lei gewoonlik nie tot opbrengsverlies nie.<\/li>\r\n<\/ol>\r\nLet Wel: Raadpleeg \u2018n gekwalifiseerde landboukundige vir meer lokaliteit spesifieke toepassings. Die resultate waarna in hierdie artikel verwys word, is onder spesifieke omstandighede verkry en daarom nie algemeen onder alle omstandighede toepasbaar nie.\r\n
      Verwysings:\r\nADRIAANSE F.G., 1990. Effects of nitrate: ammonium ratios, times of application and prolificacy on nitrogen response of Zea mays L. Ph. D. University of the Free State.<\/strong>\r\nADRIAANSE F. G. 1991. Ongepubliseerde navorsingsverslag oor stikstofplasing, LNR-IGG Potchefstroom.<\/strong>\r\nADRIAANSE, F. G., 2012. KAN of ureum: voor-plant, met-plant of na-plant. S A<\/strong>\r\nGraan\/Grain 05\/12<\/strong>\r\nADRIAANSE, F. G. & SCHMIDT. 2003. N-aanbevelings volgens N-ontledings in<\/strong>\r\ndie grond \u2013 die enigste antwoord. S A Graan\/Grain. 7\/03.<\/strong><\/h6>","_af_post_name":"die-verskil-in-toksisiteit-tussen-kan-en-ureum","_af_post_excerpt":"","_af_post_title":"Die verskil in toksisiteit tussen KAN en ureum","_fr_post_content":"","_fr_post_name":"","_fr_post_excerpt":"","_fr_post_title":"","_pt_post_content":"","_pt_post_name":"","_pt_post_excerpt":"","_pt_post_title":"","edit_language":"fr","footnotes":""},"categories":[14,6,15,5],"tags":[109,100,101,102,110,108,107,103],"class_list":["post-23","post","type-post","status-publish","format-standard","has-post-thumbnail","category-fertilizer-products","category-nitrogen","category-nitrogen-fertilizer-products","category-fertilizers","tag-can","tag-erik-adriaanse","tag-fg-adriaanse","tag-lan","tag-limestone-ammonium-nitrate","tag-n-toxicity","tag-nitrogen-toxicity","tag-urea"],"_links":{"self":[{"href":"https:\/\/agrispex.co.za\/fr\/wp-json\/wp\/v2\/posts\/23","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/agrispex.co.za\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/agrispex.co.za\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/agrispex.co.za\/fr\/wp-json\/wp\/v2\/users\/15"}],"replies":[{"embeddable":true,"href":"https:\/\/agrispex.co.za\/fr\/wp-json\/wp\/v2\/comments?post=23"}],"version-history":[{"count":44,"href":"https:\/\/agrispex.co.za\/fr\/wp-json\/wp\/v2\/posts\/23\/revisions"}],"predecessor-version":[{"id":1438,"href":"https:\/\/agrispex.co.za\/fr\/wp-json\/wp\/v2\/posts\/23\/revisions\/1438"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/agrispex.co.za\/fr\/wp-json\/wp\/v2\/media\/1296"}],"wp:attachment":[{"href":"https:\/\/agrispex.co.za\/fr\/wp-json\/wp\/v2\/media?parent=23"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/agrispex.co.za\/fr\/wp-json\/wp\/v2\/categories?post=23"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/agrispex.co.za\/fr\/wp-json\/wp\/v2\/tags?post=23"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}