Response of maize to rainwater harvesting and conservation techniques on the Glen/Oakleaf ecotope
Loading...
Date
2016-11
Authors
Chuene, Mardulate Motlalepula
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State
Abstract
English: Rainfall in semi-arid areas fluctuates constantly and it is difficult for farmers to increase crop productivity. The rainfall is insufficient, erratic and unreliable, which is associated with poor water availability due to increased water losses such as high evaporation from the soil (Es) due to rising temperatures, runoff (R) and deep drainage (D). These unproductive losses (Es, R & D) contribute to inefficient rainfall, which increases food insecurity and poverty. Crops produced in semi-arid areas under rainfed agriculture by smallholder farmers are usually produced using conventional tillage (CON). This system uses a moldboard plough, which turns and exposes the soil and therefore increases Es and R while organic matter is decreasing. In many semi-arid areas, research was conducted to improve crop production.
One of these researches was conducted in South Africa at the Thaba Nchu villages where the Agricultural Research Council (ARC-ISCW) introduced an In-field rainwater harvesting
technique (IRWH) to increase efficiency and use of limited water. This system was used to
reduce unproductive water losses especially Es and R, to optimize rainwater productivity
(RWP). This study was conducted to investigate the ability of different rainwater harvesting
and conservation (RWH&C) techniques to produce higher yield in using and storing water
efficiently under rainfed conditions of Glen/Oakleaf ecotope.
To test the hypothesis, a field experiment was conducted in a semi-arid area under rainfed
conditions at the Glen/Oakleaf ecotope in Bloemfontein. The area is characterized by an
average long-term (LT) rainfall in the growing period of 262 mm and an evaporation demand of 758 mm. Treatments used were In-field rainwater harvesting with a 2.0 m runoff strip (IRWH-2.0m), In-field rainwater harvesting with a 2.4 m runoff strip (IRWH-2.4m), Mechanised basins (MB), Minimal tillage (MIN), Darling plough (DAL) and Conventional tillage (CON). The experiment was conducted in two consecutive growing seasons (2008/09 & 2009/10) laid out in a complete block design (RCBD), with four replications and six treatments. The study was aimed to identify the most appropriate RWH&C techniques that will increase rainwater availability throughout the growing season to increase crop productivity by maximizing yield per unit of water.
The first season had 260 mm of rainfall, and was considered a dry season, the second season was a wetter season with 486 mm. rainfall. During the first growing season rainfall was 8% lower than the LT (262 mm), while in the second season it could be considered wetter as the rainfall was 85% higher than LT. Rainfall during Vp was greater than LT during both seasons
with 19% and 49% higher rainfall respectively. During the first dry season rainfall at Rp was
41% lower than LT and 160% higher during the second wet season. A short growing maize
cultivar was chosen as a crop indicator, PAN 6Q-521R with a growing period of 120 days
from planting to harvest.
The ecotope had a fine sandy loam soil with a depth of ± 1200 mm and a clay content of
15% in the A horizon and 30% in the B horizon. Land preparation was done by loosening up the soil to avoid compaction before implementing the different RWH&C techniques and
CON treatment. Therefore, CON treatment was tilled with a moldboard plough. Only CON
was ploughed during the second season and other treatments were not implemented.
Evapotranspiration was calculated by using the soil water balance equation for dryland crop production. Soil water content was measured with a neutron water meter and crop water efficiencies (RSE, WUE, PUE & RWP) were calculated. Maize height, stem diameter, leaf area index and biomass were measured in four growth development stages only during the 2008/09 growing season while grain yield was measured during both seasons.
The first objective is explained in chapter 4, which was to evaluate soil water balance and
different rainwater efficiency (Rainwater storage efficiency (RSE), Water use efficiency
(WUE) and Precipitation use efficiency (PUE)) of various RWH&C techniques against CON
tillage for possible adoption by smallholder farmers to increase crop productivity. The Plant
available water at planting, tasseling and harvest were higher with RWH&C techniques
compared to the CON treatment during both growing seasons. Similarly soil water content
during both seasons were higher with RWH&C techniques compared to CON tillage.
However, during the first growing season at 13 DAP, the soil water content of all treatments
was above the DUL line of 280 mm indicating that D could have occurred. MIN treatment
was shown to have the highest runoff percentage followed by CON tillage. The ET of
RWH&C techniques during the dry season (2008/09) was higher than that of CON tillage,
however more water was lost through Es with RWH&C techniques. During the second
season RWH&C techniques excluding MIN tillage had higher ET compared to CON tillage
and higher Es. RSE was not included during the first season due to late implementation of
treatments. During the second season IRWH-2.0 m and IRWH-2.4 m treatments had the
lowest RSE compared to MIN CON, MB and DAL treatments. The results showed that
IRWH-2.0m treatment had the lowest WUEET during both seasons. During the dry season
(2008/09) WUEEV based on transpiration was highest on the IRWH-2.0m treatment and
during the wetter season (2009/10) CON treatment had the highest WUEEV. During the
2009/10 season, RWH&C techniques excluding IRWH-2.0m showed to have greater PUEfg than that of CON treatment. During the dry season the results showed a higher PUEg with RWH&C techniques than that on CON treatment; however during the wet season PUEg was higher with IRWH-2.4m treatment compared to that of CON treatment. For both seasons (2008/09 & 2009/10) IRWH-2.4m, MIN and MB techniques had greater RWP compared to CON tillage. Overall the results showed that RWH&C techniques collected and stored water better during the dry season than in the wet season.
The second objective of this study was to determine maize performance under the various
RWH&C techniques compared to CON tillage on the Glen/Oakleaf ecotope. This objective is explained in Chapter 5. Plant height, stem diameter and LAI data were collected only during the first season and the study revealed that maize plants exposed to the CON treatment were taller and thicker compared to RWH&C techniques. During the Vp, plants exposed to the CON treatment had lower LAI than those exposed to RWH&C techniques. At 66 DAP there were no differences between the treatments, however, at 90 DAP plants exposed to the CON treatment had higher LAI. During the Vp of the first season at 30 DAP, plants exposed to the IRWH-2.4m treatment had greater biomass than all other treatments, however during the second season plant biomass exposed to the IRWH-2.0m, and MB treatments were greater than those exposed to the CON treatment. During the first season at 45 DAP plants biomass exposed to the MIN and IRWH-2.0m treatments were both greater than that of other treatments and during the second season plants exposed to the CON treatment were higher than those exposed to the RWH&C techniques. During the Rp at 66 DAP, in both seasons plants exposed to the DAL treatment produced less biomass than in all the other treatments.
During the 2008/09 season at 90 DAP, plants exposed to the IRWH-2.4m, MIN and CON
treatments were higher than DAL. However, in the second season at 90 DAP plants showed no difference in biomass between treatments. Grain yield differed between the two seasons due to differences in rainfall. During the dry season of 2008/09, RWH&C techniques had higher grain yield than that of CON treatment. In the wet season of 2009/10 IRWH-2.4m was the only RWH&C technique with a high yield. It was concluded that RWH&C techniques were most likely to perform better in dry conditions than during wetter conditions. During the wet season only IRWH-2.4m techniques performed better than that of CON treatments.
Afrikaans: Reenval wissel in semi ariede gebiede, wat dit moeilik maak vir boere om gewas produksie te verbeter. Die reenval is min, onvoorspelbaar en wisselvallig. Dit veroorsaak min water beskikbaarheid vir die volgende redes, verdamping (Es), verhoogde temperature, afloop (R) en diep dreinering (D). Hierdie onproduktiewe verliese (Es, R & D)dra by tot swak reenval, wat voedsel onveiligheid bevorder en sodoende armmoede tot gevolg het. Gewasse wat geproduseer word in semi ariede gebiede onder reenwater toestande, word gewoonlik op die Konvensionele Bewerkings Metode (CON) geproduseer. Hierdie sisteem gebruik gewoonlik ‘n ploegskaar, wat die grond omdop en blootstel aan die son, dit bevorder Es en R terwyl organiese materiaal in die grond verminder word. Navorsing is in baie semi ariede gebiede gedoen om te bepaal of water retensie en gewas produksie kan verbeter. Een van die gebiede is in Suid Afrika, by die Thaba Nchu nedersettings, waar die Landbounavorsings Raad (ARC-ISCW) ‘n Binneveld Reenwater Oes Tegniek (IRWH) gevestig het. Dit het die doeltreffendheid en gebruik van reenwater baie verbeter. Die sisteem word gebruik om watervermorsing as gevolg van Ese n R baie te beperk, en dit veroorsaak dat die beskikbare water geoptimaliseer word. Hierdie studie is gedoen om vas te stel of verskillende grond bewerkings tegnieke en verskillende reenwater oes metodes (RWH&C) ‘n verskil sal maak aan gewas produksie om sodoende armmoede te beveg. Om hierdie hipotese te toets, is gebruik gemaak van ‘n semi ariede gebied wat bestuur word onder reenval toestande, die Glen/Oakleaf ekotoop net buite Bleomfontein. Hierdie gebied word gekenmerk deur ‘n gemiddelde langtermyn (LT) reenval in die groeiseisoen (262 mm) en ‘n verdampings anvraag van 758 mm. Die behandelings wat toegepas is, is Binneveld reenwater opvangs met ‘n 2 m afloop strook (IRWH-2m), Binneveld reenwater opvangs met ‘n 2.4 m afloop strook (IRWH-2.4m), Gemeganiseerde dammetjies (MB), Minimum bewerking (MIN), Daling ploeg (DAL) en Konvensionele bewerking (CON). Die eksperiment was gedoen oor twee opeenvolgende groeiseisoene (2008/09 & 2009/10), uitgele in ‘n volledige blok formasie (RCBD), met vier replikas en ses behandelings. Die studie se doel is om die beste tegniek te vind wat reenwater beskikbaarheid sal vermeerder, sodat gewas produksie kan verhoog, en daar ‘n optimale opbrengs per eenheid water sal wees. Die eerste seisoen het 260 mm reen gehad, en was beskou as ‘n droe jaar. Die tweede seisoen was beskou as die natter jaar met ‘n reenval van 486 mm. Gedurende die eerste seisoen was die reenval 8% laer as die LT (262 mm), terwyl die tweede seisoen se reenval 85% hoer was as LT. Reenval gedurende Vp was groter as LT in beide seisoene met 19% en 49% onderskeidelik. Gedurende die eerste droe seisoen was die reenval by Rp 41% laer as LT en in die tweede nat seisoen was dit 160% hoer. ‘n Kort groeiende mielie kultivar is gekies as die gewas aanwyser, PAN 6Q-521R, met ‘n groei seisoen van 120 dae van plant tot oes. Die ekotoop het ‘n fyn sanderige leem grond met ‘n diepte van min of meer 1 200 mm en ‘n klei inhoud van 15% in die A horison en ‘n 30% klei inhoud in die B horison. Die land voorbereiding was gedoen deur die grond los te maak om kompaksie te vermy voor die verskillende RWH&C tegnieke geimplimenteer is. Die CON lande is met ‘n gewone ploeg behandel, net die CON lande is in die tweede seisoen ook geploeg. Die evapotranspirasie was bereken deur die grond water balans vergelyking vir droe land gewas produksie te gebruik. Die grond water inhoud was gemeet deur ‘n neutron water meter en die gewas water doeltreffendheid (RSE, WUE, PUE & RWP) is bereken. In die 2008/09 seisoen is die mielie hoogte, stam deursnee, blaar oppervlak index en biomassa gemeet in vier verskillende groei stadiums. Die gewas produksie was in altwee seisoene gemeet. Die eerste objektief is in hoofstuk 4 verduidelik, dit was om die grond water balans en die reenwater doeltreffendheid te evalueer. Daar is gekyk na reenwater stoor tegnieke (RSE), water verbruik doeltreffendheid (WUE) en neerslag doeltreffendheid (PUE) van verskillende RWH&C tegnieke, teenoor CON tegnieke, sodat daar bepaal kan word of daar ‘n meer doeltreffende tegniek is wat aan boere voorgele kan word om gewas produksie te verbeter. Die plant beskikbare water by plant, pluimverskyning en oestyd was hoer met die RWH&C tegnieke as by die CON tegniek op dieselfde tye. Die grond water inhoud in beide seisoene was ook hoer met die RWH&C tegnieke as met die CON tegniek. Die MIN tegniek het die meeste afloop gehad, gevolg deur die CON tegniek. Die ET van die RWH&C tegnieke was hoer in die droe seisoen (2008/09) as die van die CON tegniek, alhoewel meer water verlore gegaan het deur Es in die RWH&C tegnieke. Gedurende die tweede seisoen het die RWH&C tegnieke (uitsluitend die MIN tegniek) hoer ET gehad in vergelyking met die CON tegniek, e nook hoer Es. RSE was nie ingesluit in die eerste seisoen nie as gevolg van die laat toediening van tegnieke. Gedurende die tweede seisoen het die IRWH-2m en die IRWH-2.4m die laagste RSE gehad. Die uitslae het gewys dat die IRWH-2m die laagste WUE in albei seisoene gehad het. Gedurende die droe seisoen (2008/09) was die WUE gebasseer op transpirasie die hoogste op die IRWH-2m behandeling, en gedurende die nat seisoen (2009/10) het die CON tegniek die hoogste WUE gehad. Gedurende die 2009/10 seisoen het die IRWH&C tegnieke (uitsluitend die IRWH-2m tegniek) ‘n groter PUE gehad as die CON tegniek. In die droe seisoen het die RWH&C tegnieke ‘n hoer PUE gehad. Die algehele resultate het getoon dat die RWH&C tegnieke beter water versamel en gestoor het in die droe seisoen as in die nat seisoen. Die tweede objektief van die studie was om te bepaal of die mielie gewas beter presteer onder ander tegnieke as die CON tegniek. Hierdie objektief is in hoofstuk 5 bespreek. Plant hoogte, stam dersnee en LAI data was versamel net in die eerste seisoen, en dit het getoon dat plante wat blootgestel was aan die CON tegniek groter en swaarder was as die plante wat aan die ander tegnieke blootgestel was. Gedurende Vp was die LAI van die plante wat aan die CON tegniek blootgestel was laer as die LAI van die plante wat aan die RWH&C tegnieke blootgestel was. By 66 DAP was daar geen verskille tussen die onderskeie tegnieke nie, maar op 90 DAP was die LAI van die plante op die CON tegniek hoer. Gedurende die Vp van die eerste seisoen, by 30 DAP, was die plant biomassa op die IRWH-2m tegniek en die plante op die MB tegniek meer as die plante op die CON tegniek. Gewas produksie het verskil tussen die twee seisoene (2008/09 en 2009/10), as gevolg van die verskil in reenval. Gedurende die droe seisoen (2008/09) het die RWH&C tegnieke meer produksie getoon, en in die natter seisoen (2009/10) het die IRWH-2m tegniek die beste produksie gehad. Dit was bepaal dat die RWH&C tegnieke beter werk in droe jare, en dieselfde of slegter vaar in nat jare as die CON tegniek.
Afrikaans: Reenval wissel in semi ariede gebiede, wat dit moeilik maak vir boere om gewas produksie te verbeter. Die reenval is min, onvoorspelbaar en wisselvallig. Dit veroorsaak min water beskikbaarheid vir die volgende redes, verdamping (Es), verhoogde temperature, afloop (R) en diep dreinering (D). Hierdie onproduktiewe verliese (Es, R & D)dra by tot swak reenval, wat voedsel onveiligheid bevorder en sodoende armmoede tot gevolg het. Gewasse wat geproduseer word in semi ariede gebiede onder reenwater toestande, word gewoonlik op die Konvensionele Bewerkings Metode (CON) geproduseer. Hierdie sisteem gebruik gewoonlik ‘n ploegskaar, wat die grond omdop en blootstel aan die son, dit bevorder Es en R terwyl organiese materiaal in die grond verminder word. Navorsing is in baie semi ariede gebiede gedoen om te bepaal of water retensie en gewas produksie kan verbeter. Een van die gebiede is in Suid Afrika, by die Thaba Nchu nedersettings, waar die Landbounavorsings Raad (ARC-ISCW) ‘n Binneveld Reenwater Oes Tegniek (IRWH) gevestig het. Dit het die doeltreffendheid en gebruik van reenwater baie verbeter. Die sisteem word gebruik om watervermorsing as gevolg van Ese n R baie te beperk, en dit veroorsaak dat die beskikbare water geoptimaliseer word. Hierdie studie is gedoen om vas te stel of verskillende grond bewerkings tegnieke en verskillende reenwater oes metodes (RWH&C) ‘n verskil sal maak aan gewas produksie om sodoende armmoede te beveg. Om hierdie hipotese te toets, is gebruik gemaak van ‘n semi ariede gebied wat bestuur word onder reenval toestande, die Glen/Oakleaf ekotoop net buite Bleomfontein. Hierdie gebied word gekenmerk deur ‘n gemiddelde langtermyn (LT) reenval in die groeiseisoen (262 mm) en ‘n verdampings anvraag van 758 mm. Die behandelings wat toegepas is, is Binneveld reenwater opvangs met ‘n 2 m afloop strook (IRWH-2m), Binneveld reenwater opvangs met ‘n 2.4 m afloop strook (IRWH-2.4m), Gemeganiseerde dammetjies (MB), Minimum bewerking (MIN), Daling ploeg (DAL) en Konvensionele bewerking (CON). Die eksperiment was gedoen oor twee opeenvolgende groeiseisoene (2008/09 & 2009/10), uitgele in ‘n volledige blok formasie (RCBD), met vier replikas en ses behandelings. Die studie se doel is om die beste tegniek te vind wat reenwater beskikbaarheid sal vermeerder, sodat gewas produksie kan verhoog, en daar ‘n optimale opbrengs per eenheid water sal wees. Die eerste seisoen het 260 mm reen gehad, en was beskou as ‘n droe jaar. Die tweede seisoen was beskou as die natter jaar met ‘n reenval van 486 mm. Gedurende die eerste seisoen was die reenval 8% laer as die LT (262 mm), terwyl die tweede seisoen se reenval 85% hoer was as LT. Reenval gedurende Vp was groter as LT in beide seisoene met 19% en 49% onderskeidelik. Gedurende die eerste droe seisoen was die reenval by Rp 41% laer as LT en in die tweede nat seisoen was dit 160% hoer. ‘n Kort groeiende mielie kultivar is gekies as die gewas aanwyser, PAN 6Q-521R, met ‘n groei seisoen van 120 dae van plant tot oes. Die ekotoop het ‘n fyn sanderige leem grond met ‘n diepte van min of meer 1 200 mm en ‘n klei inhoud van 15% in die A horison en ‘n 30% klei inhoud in die B horison. Die land voorbereiding was gedoen deur die grond los te maak om kompaksie te vermy voor die verskillende RWH&C tegnieke geimplimenteer is. Die CON lande is met ‘n gewone ploeg behandel, net die CON lande is in die tweede seisoen ook geploeg. Die evapotranspirasie was bereken deur die grond water balans vergelyking vir droe land gewas produksie te gebruik. Die grond water inhoud was gemeet deur ‘n neutron water meter en die gewas water doeltreffendheid (RSE, WUE, PUE & RWP) is bereken. In die 2008/09 seisoen is die mielie hoogte, stam deursnee, blaar oppervlak index en biomassa gemeet in vier verskillende groei stadiums. Die gewas produksie was in altwee seisoene gemeet. Die eerste objektief is in hoofstuk 4 verduidelik, dit was om die grond water balans en die reenwater doeltreffendheid te evalueer. Daar is gekyk na reenwater stoor tegnieke (RSE), water verbruik doeltreffendheid (WUE) en neerslag doeltreffendheid (PUE) van verskillende RWH&C tegnieke, teenoor CON tegnieke, sodat daar bepaal kan word of daar ‘n meer doeltreffende tegniek is wat aan boere voorgele kan word om gewas produksie te verbeter. Die plant beskikbare water by plant, pluimverskyning en oestyd was hoer met die RWH&C tegnieke as by die CON tegniek op dieselfde tye. Die grond water inhoud in beide seisoene was ook hoer met die RWH&C tegnieke as met die CON tegniek. Die MIN tegniek het die meeste afloop gehad, gevolg deur die CON tegniek. Die ET van die RWH&C tegnieke was hoer in die droe seisoen (2008/09) as die van die CON tegniek, alhoewel meer water verlore gegaan het deur Es in die RWH&C tegnieke. Gedurende die tweede seisoen het die RWH&C tegnieke (uitsluitend die MIN tegniek) hoer ET gehad in vergelyking met die CON tegniek, e nook hoer Es. RSE was nie ingesluit in die eerste seisoen nie as gevolg van die laat toediening van tegnieke. Gedurende die tweede seisoen het die IRWH-2m en die IRWH-2.4m die laagste RSE gehad. Die uitslae het gewys dat die IRWH-2m die laagste WUE in albei seisoene gehad het. Gedurende die droe seisoen (2008/09) was die WUE gebasseer op transpirasie die hoogste op die IRWH-2m behandeling, en gedurende die nat seisoen (2009/10) het die CON tegniek die hoogste WUE gehad. Gedurende die 2009/10 seisoen het die IRWH&C tegnieke (uitsluitend die IRWH-2m tegniek) ‘n groter PUE gehad as die CON tegniek. In die droe seisoen het die RWH&C tegnieke ‘n hoer PUE gehad. Die algehele resultate het getoon dat die RWH&C tegnieke beter water versamel en gestoor het in die droe seisoen as in die nat seisoen. Die tweede objektief van die studie was om te bepaal of die mielie gewas beter presteer onder ander tegnieke as die CON tegniek. Hierdie objektief is in hoofstuk 5 bespreek. Plant hoogte, stam dersnee en LAI data was versamel net in die eerste seisoen, en dit het getoon dat plante wat blootgestel was aan die CON tegniek groter en swaarder was as die plante wat aan die ander tegnieke blootgestel was. Gedurende Vp was die LAI van die plante wat aan die CON tegniek blootgestel was laer as die LAI van die plante wat aan die RWH&C tegnieke blootgestel was. By 66 DAP was daar geen verskille tussen die onderskeie tegnieke nie, maar op 90 DAP was die LAI van die plante op die CON tegniek hoer. Gedurende die Vp van die eerste seisoen, by 30 DAP, was die plant biomassa op die IRWH-2m tegniek en die plante op die MB tegniek meer as die plante op die CON tegniek. Gewas produksie het verskil tussen die twee seisoene (2008/09 en 2009/10), as gevolg van die verskil in reenval. Gedurende die droe seisoen (2008/09) het die RWH&C tegnieke meer produksie getoon, en in die natter seisoen (2009/10) het die IRWH-2m tegniek die beste produksie gehad. Dit was bepaal dat die RWH&C tegnieke beter werk in droe jare, en dieselfde of slegter vaar in nat jare as die CON tegniek.
Description
Keywords
Rainwater harvesting, Maize, Soil water balance, Rainfall storage efficiency, Water use efficiency, Rainwater productivity, Water harvesting -- South Africa -- Free State -- Thaba Nchu, Water -- Storage, Crops, Dissertation ((M.Sc.Agric. (Soil, Crop and Climate Sciences))--University of the Free State, 2016