Evaluation of tine and disc openers for wheat production in soils of different qualities and with various crop residue levels.

Thesis (MA)--Stellenbosch University, 2018.

ENGLISH ABSTRACT: The Swartland wheat producing area in the Western Cape is characterised by a Mediterranean-type climate and receives about 80% of the rainfall in winter season, which is particularly favourable for wheat (Triticum aestivum) production. Currently, most farmers are implementing conservation agriculture (CA) systems seeking to minimise soil disturbance, increase crop diversity and to retain crop residues on the soil surface. No-till seed-drills are used to establish wheat. Although most farmers rely on tine openers seed-drills to establish wheat, disc openers are becoming more popular due to the belief that discs will disturb less soil when compared to tine openers. The aim of the study was to compare tine and disc openers and the effects of soil quality and crop residue on wheat production, by evaluating establishment, biomass production, leaf area index (LAI), wheat grain yield, thousand kernels mass (TKM), ear-bearing tillers (EBT), Hectolitre mass (HLM) and soil disturbance. The first objective was to evaluate the degree of soil disturbance caused by tine or disc openers in the soils of different qualities. The second objective was to evaluate the establishment of wheat planted with a tine or disc opener in different quality soils with different residue levels. Trials were conducted in 2016 and 2017 at Langgewens Research Farm in the Swartland. In both years, wheat was established in dry soils. The seasonal rainfall for 2017 was lower than for 2016. Contrary to what was expected, soil disturbance did not differ (P>0.05) between tine or disc openers, regardless of soil quality. The tine and disc openers performed similarly in the 2016 and 2017 seasons with regard to plant population, LAI, EBT, grain yield, and TKM regardless of soil quality with residue level (P>0.05). Biomass production at physiological maturity showed treatment effects (P<0.05) in 2016. On low quality soils where disc openers were used, a significant increase in biomass production was recorded compared tine openers on medium residues. In the 2017 season, residue level has caused poor wheat establishment that resulted in lower biomass production compared to 2016. Disc openers achieved the lowest (P<0.05) HLM on low quality soils with low residue levels compared to tine openers. Disc openers also resulted in the highest (P<0.05) HLM on high soil quality with high residue level. Therefore, either a disc or tine opener can be used by wheat producers for planting wheat in the Swartland. Further research is suggested which should focus on an economic evaluation of disc and tine openers to give farmers further insight when choosing between the two.

AFRIKAANSE OPSOMMING: Die Swartland koringproduksie-area in die Wes-Kaap word deur ʼn Mediterreënse klimaat gekenmerk en ontvang omtrent 80% van die reënval in die winterseisoen, wat veral gunstig vir koring-(Triticum aestivum)-produksie is. Tans implementeer meeste boere bewaringsboerderypraktyke wat minimum-grondversteuring, verhoogde gewasdiversiteit en behoud van oesreste op die grondoppervlak insluit. Geen-bewerkingsaaimasjiene word gebruik om koring te vestig. Alhoewel meeste boere op tandoopmakers staatmaak om koring te vestig, word skyfoopmakers meer populêr omdat daar geglo word dat skyfoopmakers die grond minder as tandoopmakers versteur. Die doel van die studie was op die effek van grondkwaliteit en oesreste op koringproduksie te evalueer, deur vestiging, biomassa-produksie, blaaroppervlakindeks (LAI), graanopbrengs, duisendkorrelmassa (TKM), aardraende halms (EBT), skepelmassa (HLM) en grondversteuring te evalueer. Die eerste objektief was om die hoeveelheid grondversteuring wat deur tand- en skyfoopmakers veroorsaak word in gronde met verskillende kwaliteite, te evalueer. Die tweede objektief was om vestiging van koring wat met tand- of skyfoopmakers geplant word in gronde met verskillende kwaliteite en deur verskillende oesresvlakke, te evalueer. Proewe was in 2016 en 2017 op Langgewens Navorsingsplaas in die Swartland uitgevoer. In beide jare was koring in droë grond gevestig. Die seisoenale reënval vir 2017 was laer as vir 2016. Bo verwagting het grondversteuring nie tussen tand- en skyfoopmakers verskil nie (P>0.05), ongeag grondkwaliteit. Die tand- en skyfoopmakers het in beide 2016 en 2017 soortgelyk in terme van plantpopulasie, LAI, EBT, graanopbrengs en TKM presteer, ongeag grondkwaliteit en oesresvlakke. Biomassaproduksie by fisiologiese rypstadium het behandelingseffekte in 2016 getoon (P<0.05). Waar skyfoopmakers op lae grondkwaliteit gebruik was, was biomassaproduksie hoër as wanneer tandoopmakers deur mediumvlakke van oesreste gebruik was. In 2017 het oesresvlakke ʼn swakker vestiging as in 2016 veroorsaak, wat tot ʼn laer biomassaproduksie gelei het. Skyfoopmakers het die laagste (P<0.05) HLM op lae grondkwaliteit veroorsaak. Skyfoopmakers het ook die hoogste (P<0.05) HLM op hoë grondkwaliteit met hoë oesresvlakke veroorsaak. Daarom kan óf ʼn tand óf ʼn skyfoopmaker deur koringprodusente in die Swartland gebruik word. Verdere navorsing word voorgestel om die ekonomie van tand- en skyfoopmakers te bepaal, om sodoende boere verdere insig te gee wanneer daar tussen die oopmakers gekies moet word.

Masters