In this study, attempts were made to investigate the growth and yield performance of a Bangladeshi bread wheat cultivar (Sonalica) under the influence of three different nitrogen fertilizer levels and one concentration level of ComCat ® , a commercial bio-stimulant, applied either as a seed treatment before planting or as a foliar spray on seedlings at the 3- leaf growth stage, under glasshouse conditions. Initially the South African (RSA) standard N-level for winter wheat was taken as the medium N- level together with a down scaled (low) and an up scaled (high) rate during the 2001 season in order to ascertain the optimum level. However, it was observed that the Bangladeshi cultivar could not tolerate the RSA standard (medium rate) for nitrogen application. After germination all plants fertilized with the medium and high nitrogen rates, died off. Subsequently, this N-level was taken as the medium level for the 2002 trial and a new down scaled (low) and up scaled (high) N-level was calculated and applied, together with the two ComCat ® treatments. Overall, even though the nitrogen fertilizer application was scaled down substantially during the 2002 growing season, the response of this bread wheat cultivar, in terms of growth and yield, was more positive at the lowest N-level. Results obtained during 2002 consistently confirmed that the application of ComCat ® , especially as a foliar spray at stage 13 of seedling development, affected the vegetative growth of plants. However, the enhancing effect of the bio-stimulant was more pronounced on yie ld, in terms of both the increase in number of kernels and kernel dry mass per plant. Finally, the results of this study and several previous unpublished reports strongly indicate that application of a bio-stimulant such as ComCat ® , in combination with an optimum nitrogen regime, can result in the improvement of yield under glasshouse conditions. In future research attention should be given to the combined effect of ComCat ® and other macro-nutrients, as well as the potential to decrease fertilizer applications when a bio-stimulant is applied in combination, under field conditions.

Soil properties (biological and chemical) and crop response are dependent on the inherent soil organic matter content. Since South African soils are naturally low in organic matter content commercial humates serve as attractive soil amendments in improving soil quality. This is the result of commercialisation giving the impression that humates have biological and chemical properties similar to those in soil humus. In an attempt to substantiate these claims three separate experiments were conducted at the University of the Free State to examine the effect of K-humate on soil properties and wheat response during the 2006 growing season. The biological (bacterial and fungal count) response was evaluated in growth chambers by applying three different K-humate products at rates of 0, 3 and 5 L ha-1 in a band on a red loamy sand topsoil. Soil cores were sampled on a weekly basis for six weeks and microscopically analysed. Bacterial and fungal count differed significantly as a result of the product by application rate interaction but no consistency was found. Over time both the bacterial and fungal activity increased rapidly for week 2 and 3 but decreased at week 3 for the bacteria. Both the organismsâ reactions stabilised from week 3 to 6. The chemical soil properties were also tested in growth chambers but only K-humate (single product) was applied as a coating on granular 2:3:2 (22) fertiliser at 0 and 3 L ha-1 in a band 50 mm below the soil surface. The chemical soil properties showed no response after 5 months to the application of K-humate. A glasshouse experiment was also conducted to evaluate the growth and yield response of wheat on three textural class topsoilâs (8, 22 and 37% clay) and four K-humate applications (0 L ha-1, 3 L ha-1 single application, and 3 and 6 L ha-1 split application â 50% at planting and 50% at tillering). K-humate as a coating on 2:3:2 (22) granular fertiliser was banded and Greensulph (27) topdressed at the required fertiliser rate for a yield potential of 8 t ha-1. Plant growth parameters were analysed at tillering, stem elongation and maturity, both above- and below-ground. Virtually no significant influences were found with the K-humate application rate and soil texture interaction on the measured parameters. Notwithstanding this, positive effects were noticed and a split application whereof half of the K-humate was applied at planting and the other half at tillering showed the best results. A field experiment was also conducted to examine K-humates influence on wheat growth and yield. Two experiments was conducted, one under full irrigation (700 mm) with a yield potential of 8 t ha-1 and the other supplementary irrigation (350 mm) with a yield potential of 4 t ha-1. K-humate was applied as a coating on granular 2:3:2 (22) fertiliser and bandplaced either as a single application (0, 1.5, 3, 5 and 6 L ha-1) or a split application (5 and 6 L ha-1) 50% at planting and 50% (K-humate as a coating on Greensulph (27)) at tillering. Irrigation was applied using a line source irrigation system. The field experiment confirmed the results obtained in the glasshouse with virtually no significant effects as a result of the applied K-humate on the measured plant parameters.

One of the biggest constraints to the expansion of the walnut industry in South Africa, is the availability of good quality and cost effective plant material. Since walnuts are more difficult to propagate vegetatively than most fruit and nut species, controlled conditions are required to ensure grafting success. Hot callus grafting is a bench grafting procedure subjecting grafted trees to controlled, elevated temperature and humidity, and has been implemented successfully in several countries to increase grafting success of walnut. Until now, hot callus grafting has not been investigated as a possible walnut propagation method in South Africa. The present study assessed method of heat supply and time of grafting, as important factors determining grafting success of two walnut cultivars grafted onto Juglans regia rootstocks under hot callus conditions. Although neither method of heat supply provided definite superior grafting success, localized heating of graft unions in a heated trench, gave more consistent results than heating the entire grafted tree in a heated room. Both methods seemed promising, since acceptable grafting success was obtained in some instances with both the heated trench and room. Post-grafting shoot growth on the other hand, was significantly higher for the heated trench than for the room. Both methods did, however, result in trees of a suitable size for orchard establishment after only one growing season. Results further indicated that exposure to increased temperature for a period of 25 days is more than sufficient for callus development of walnut, and very little is gained by heating grafted trees for longer. Earlier grafting, before the onset of bud break of cultivar and/or rootstock, generally resulted in improved grafting success and drastically increased shoot growth during the first growing season, providing grafted trees of saleable size in a shorter time. There were no clear differences regarding callus formation, grafting success or survival between the two cultivars evaluated, âChandlerâ and âSerrâ. As expected, more vigorous post-grafting growth was observed for âSerrâ, since it is the more vigorous grower of the two. A separate hot callus grafting trial, using Paradox rootstocks, also indicated that the type of rootstock utilized in hot callus grafting may impact grafting success. More consistent results were obtained with all four cultivars grafted onto this hybrid rootstock, than with J. regia rootstocks in the preceding trial. For both J. regia and Paradox rootstocks, survival of trees through the first growing season was still unacceptably low, although results were comparable to that of other studies. Since results were available for a single season only, conclusions should be regarded as preliminary. Nevertheless, findings clearly illustrated the potential value of hot callus grafting as propagation method for walnut in South Africa and lay a foundation for the establishment of propagation guidelines using this approach.

Soi ls vary a t all levels of observation. When describing soil physical or chemi cal propert ies we ini t i a l ly think in terms of homogeneous mat e r ial. However, for character izing the land use abi l i ty i t is necess ary to consider varia b i l ity within and between s o i l map uni ts as soils vary significantly over a land and within a homogeneous soil. The combina tions of knowledge about soi l in t e r r e l at ionships and the represent at i on of the soi l var i abi l i ty will be useful in the process of characterizing the var iabil i t y of soi l properties for dif f e rent land use abili t ies, for example precision agriculture. The obj e c t i ves of this study were therefore to (i) characterize the spat i a l var i a tion of sel e c t ed soil properties in and between map uni ts (i i ) describe the relationship between physica l proper t i es of sel e c ted soi l forms and the root densi ty of mai ze ( i i i ) characteri z e the hydrology of the Tukulu, Sepane and Bloemda l s o i l forms a t Paradys. A field experiment was conduct ed on a 55 ha c u l tiv ated f ield on the experimental farm of the University of the Free State, Paradys (S -32°35â21ââ, E -77°43â6ââ). The experimen t a l site was sub divided in to 75 experimen t a l p l o t s . For object i v e 1 a l l 75 plots were analysed for pH, Ca, K, Mg, Na and 7 texture classes . For object ive 2, 13 plots were sel ected from the 75 experimental plo ts to cover a range of relat i ve dry biomass yield plots. Root samples and soil samples were t aken per mas t e r horizon. They wer e analysed for s i l t + clay content , wat e r s table aggregates, modulus of rupture, bulk density and organic carbon content . For objective 3 , three modal profiles were sel e c ted and the instantaneous prof i le method was used to descr ibe the volumet r ic wetness â time relationship, the hydraul i c head â depth rel a t i onships and the hydraulic conductivit y . I t was clear th a t mos t of the soi l physical and chemical prope r t ies had a s t rong relationship with clay. It was found that there was a higher vari a tion between map uni t s than within map uni t s . Despite any var iat ion Inverse Distance Weigh ting (IDW) fai r ly accurately predicted the varia tion with in map uni ts varying f rom 97% to 99% i r r espect ive of hor i zon or s o i l . I t also accur a tely predi ct ed the var iat ion between map uni t s varying f rom 91% to 94%. I t was found t h a t t h e A and C hor izon has var y ing int er rel at ionship due t o varying s i l t + clay content s. The B hor izon i s the main fact or tha t dist inguishes the three s o i l s . Th e s i l t + c l a y c o n t e n t o f t h e B h o r i z on fo r Tu k ul u v a r i ed b e t w ee n 31% an d 34%, t h e S e p a ne b e t w e e n 4 9 % a n d 5 5 % , an d t h e B lo emd a l b e t w e en 28% an d 3 4 % . The B l o e md a l h a d t h e h ig he s t r o o t l e n g t h i n d e x ( R L I ) fo l l owed by t h e S e p a n e a n d Tu ku l u . I t was clear tha t in the case of the Bloemda l and Tukulu , the C hor izon control s the hydrology, while in t h e case o f the Sepane i t i s the B hor izon . I t may be concluded that the variation in soil prope r t ies is higher between t han with in map uni t s. Soi l physical p roper t i es have a clo se int er rel at ionship and varying e f fe c t s on the RLI. The hydrology of the Bloemda l and Tukul u is influenced by the C horizon, whi le the Sepane i s in f luenced by the B horizon.

Land evaluation is currently important in South Africa. Soilscape surveys can make a contribution in this connection by bridging the gap between land type surveys and detail surveys. Land Type Dc17 (area = 237 651 ha) east of Bloemfontein include the densely populated areas near Botshabelo and Thaba Nchu. The objective of this study was to subdivide Land Type Dc17 into smaller more homogeneous land units, to estimate the area of each unit suitable for maize and sunflower production using the In-field Rainwater Harvesting technique (IRWH), and to estimate attainable yields of these crops on the available areas. The soilscape survey technique was developed to serve this goal. Soilscape is defined for this specific study as a mapping unit consisting of a portion of land mappable at a scale of 1:50 000 in such a way that it facilitates the identification of potentially arable land. Earlier Northcote (1978) described soil landscapes as areas of land that have recognizable and specifiable topographies and soils, that are capable of presentation on maps, and can be described by concise statements The delineation of 66 soilscapes was done on 1:50 000 maps. Detailed pedological investigations were made on selected pedoseque nces of some soilscapes using 1:10 000 maps, soil pits, auger holes and depth probe observations. Nine soilscapes with a total area of 82 222 ha were found non-arable. For the remaining 57 soilscapes, covering an area of 155 429 ha, the improved knowledge gained during the detail studies was extrapolated to estimate the area of each one suitable for IRWH. The result was 56 875 ha, or 24 % of the total area of Dc17. The results of previous field experiments on relevant ecotopes predict the following maize yields in tons/ha/yr: conventional tillage = 82 000; simplest type of IRWH = 127 000. It is therefore estimated that this land type can provide the staple maize diet for about 600 000 people using IRWH. The soilscape survey technique proved successful within this land type, but should be refined for application to other land types and other feasibility studies.

The in-field rainwater harvesting tillage technique (IRWH), developed by the Agriculture Research Council (ARC), has been scientifically tested on clay soils at Glen Agricultural Institute by comparing with conventional tillage (mould board and disc ploughing). They showed that the IRWH crop production technique is by far more sustainable than conventional tillage. Great progress was made with the transfer of the information to rural communities located in the Thaba Nchu district. More than a thousand households applied IRWH in their homesteads during a period of three seasons of extension. According to socio-economic surveys, IRWH contributed significantly to reduce the risk of food insecurity at household level. Some of families who had access to tractors and implements identified the need to apply the IRWH on their crop fields. A tillage workshop was held at Merino village in November 2003 where several implements were demonstrated, but no-one implement was able to create the well known surface structure of the IRWH to the satisfactory of the community. Hence, the first part of the study was designed to develop and test tractor drawn implements as a primary step for out scaling the IRWH technique. Several tractor drawn implements were designed and tested in collaboration with Bramley Engineering Company. Only two implements were further tested, viz. the ridge plough designed as a primary tillage tool for creating zero gradient contour rides, and the puddler plough designed as a secondary tillage tool for preparing the micro-basins along the ridge. These implements were demonstrated at Paradys Experimental farm of the University of the Free State to communal farmers, which indicated that the implements are acceptable to them. A land preparation procedure was developed for cultivating crop field sizes up to 150 ha in association with small scale farmers. Standard practices applied in zero tillage for weeding and pest control was adopted for IRWH. Maize was harvested with a combine harvester equipped with precision technology. Unfortunately maize planting commenced late due to the severe drought and was then disrupted by long periods of continuous rain, typical of semi-arid zones. Earlier planting areas gave yields up to 4500 kg ha-1, which provide ample proof that economical yields can be obtained on 50 â 150 ha crop fields. The study concludes that it is possible to commercialize the IRWH crop production technique and hence demonstrates the bio-physical view point that it is possible for communal and small scale farmers to practice IRWH on their crop fields. The second part of the study focused on variation in soil properties associated with the soil water storage on crop fields. For this study a 55 ha crop field under IRWH was used. Soils of the field were surveyed and the area was divided into 75 plots of equal size. These plots were used to take soil samples and soil water content. The pipette method was used for determining the clay and silt fractions of the 300 mm soil layers, while the neutron soil water meter was used for measuring the water content in the same layers. A mobile EM38, linked to a global positioning system, was used to estimate soil properties (clay plus silt content and soil water content) from the correlation between EM readings (electrical conductivity; EC, mS m-1) and the measured variables obtained in selected plots. The results showed reasonable good relationships between the EC and clay plus silt content, which allowed the estimation of a textural based management zones for the crop field. The textural relationship was further exploited to estimate the profile available water capacity (PAWC) and hence the delineation of PAWC management zones. A good correlation between EC and soil water content for the profile was obtained, which laid the foundation to estimate soil wetness spatially over the crop field. Thus, this part of the study provided conclusive evidence that it is possible to estimate the variation in soil water storage with electromagnetic induction methods. Hence it opens a new and exciting research field in soil water management that will change the landscape of precision farming in the next decade. It is envisaged that variation in soil water will be managed more intensively over large fields, especially in semi-arid zones, to optimize inputs related fertilization, planting rates, pests and weed control. The last objective of the study was to improve our understanding of how rainfall characteristics and soil physical properties influence the partitioning of rain into infiltration and runoff in the IRWH system. A mobile rainfall simulator was used to simulate rain storms of three different intensities, viz. low (33 mm h-1), medium (59 mm h-1) and high (122 mm h-1). Results obtained from the experiment demonstrated the importance of the influence of rain intensity on the infiltration parameters, such as time to runoff, time to final infiltration rate and final infiltration rate. The correlation matrix and multiple regression statistics make it possible to characterize the interaction between rainfall intensity and soil physical properties to predict the various infiltration parameters. From the infiltration-runoff relations it was clear that these soils exhibit a high potential to harvest water as required by the IRWH system. This study left the researchers with the following research challenges, namely (i) the socio-economic factors associated with the application of the mechanized IRWH technique at farm scale and (ii) the application of the EM38 to estimate soil wetness and other chemical properties in a wider range of soils and conditions.

Cotton (Gossypium hirsutum) is a globally important fibre crop. The cottonseed has a high oil and protein content and is used for human and animal consumption. Innumerable commodities are made from cotton. Annual cultivar evaluations are essential to compare the yield and quality obtained in different production areas, to obtain experimental data to recommend the most suitable cultivar for a production area. The objective of this study was to evaluate the performance of different cotton cultivars under irrigation in South Africa. The cultivars planted from the 2003/2004 season up to the 2005/2006 season were NuOPAL, DeltaOPAL, DeltaOpal RR, LS9219 and SZ9314. The localities were Loskop (Mpumalanga Province), Makhathini (KwaZulu- Natal), Rustenburg (North-West Province), Vaalharts and Upington (Northern Cape) and Weipe (Limpopo Province). The Additive Main Effects and Multiplicative Interaction (AMMI) statistical model was used to describe the effect of cultivar x environment interaction on the yield of cotton planted under irrigated conditions. It is recommended that cotton producers should plant NuOPAL, since it was selected by the AMMI model as the best performer in respect of seed cotton yield and fibre yield (kg ha-1) in fifteen out of eighteen environments.

A number of the commercially available maize cultivars were screened in order to establish their tolerance to acetochlor. These cultivars demonstrated significant differences in their tolerance, with some cultivars being tolerant and others sensitive to the herbicide. The cultivar PAN6Q521R was the most tolerant and DKC 73-76R was the most sensitive, while most other cultivars were intermediate in their sensitivity. This indicates that maize tolerance to acetochlor is genetically controlled. The influence of planting depth on maize tolerance to acetochlor was investigated using these two cultivars. Both cultivars were found to be more sensitive as the planting depth increased to 45 mm. However, seedlings of DKC 73-76R exhibited more phytotoxicity than PANQ6521R at all planting depths. The effect of seed size on acetochlor tolerance could not be determined with any clarity. Cultivar sensitivity to the herbicide as well as seed shape appeared to also play a role. In DKC 73-76R it appeared as though large flat seeds produced plants more tolerant to acetochlor than smaller flat seeds. The effect of soil type on acetochlor phytotoxicity on a tolerant (PANQ6521R) and sensitive (DKC 73-76R) maize cultivar was examined in two trials, one using an average application rate on all soils, and the second utilizing the recommended application rates for each soil. Acetochlor activity was found to be lowest on the clay loam soil (38% Clay) and highest on the sandy soil (8% Clay) in the first case, with severe phytotoxicity occurring on the latter soil. In the second trial bioactivity was similar on all soils, although greater on the sand. This indicated that the recommended application rate on sandy soils might need adjustment. The influence of temperature on maize tolerance to acetochlor was investigated at suboptimal (15/8oC), optimal (25/18oC) and supra-optimal (35/28oC) temperature regimes (day/night temperature respectively). Seedling growth of both cultivars was inhibited significantly by acetochlor at the optimum temperature regime (25/18oC). All results confirmed that DKC 73-76R was more sensitive to acetochlor than PAN6Q521R.

There is an interactive relationship between soil and hydrology. Water plays a primary role in the genesis of most soil properties and soil properties influences and governs hydrological processes. Incorporation of these processes into hydrological models is essential for water resource management. Hydrological processes are dynamic in nature with strong temporal variation, making measurements expensive, inaccurate and time consuming. Predictions of these processes, especially predictions in ungauged basins (PUB) are therefore essential. Since soil properties are both a cause and result of this interactive relationship, identifying and interpreting relevant soil properties, can reveal information on key hydrological processes. The hypothesis is then that soil properties can serve as signatures of hydrological characteristics. Identifying these and interpreting them and their relative distribution at hillslope scale can lead to better understanding of hillslope hydrological response and facilitate the formulation of conceptual hillslope hydrological models. These models can aid in the prediction of hydrological processes in ungauged basins (PUB). Hydrologically there are three main soil types namely recharge, interflow and responsive soils. Data from previous studies were utilized to accentuate the differences between these soil types. A criterion for distinguishing between two storage mechanisms (perennial and transient groundwater) in the soils of South Africa is also proposed. Two catchments in the Eastern Cape of South Africa were selected for this study: A hillslope in the upper catchment (Uc) of the Weatherley was selected to determine the impact of soil types on hydrological response. A conceptual model was developed based on soil morphological properties and their relative distribution. These morphological properties included soil depths, mottling, and clay contents. These properties indicate that there are definite recharge, interflow and responsive areas in this hillslope. The conceptual model was then evaluated with the use of climate, tensiometer, neutron water meter, hydrograph and evapotranspiration (ET) data. The conceptual model and soil information were utilised to calculate the relative contribution of streamflow generation mechanisms. Base and peakflow calculations gave a very good estimation of the actual streamflow. In the greater Bedford catchment, three sub-catchments (B3, B4 and B5) were surveyed for hydropedological purposes. All the soil properties which might influence or be influenced by the hydrology were identified and related to hydrological hillslope response. These properties include: soil type, soil depth, weathering of underlying material, and presence of CaCO3. Conceptual models of representative hillslopes in the selected catchments were developed based on the interpreted soil information. The dominant factors governing the streamflow in catchment B4&5 was shallow soils on bedrock with restricted permeability, which facilitated overland flow. In B3 the deeper soils and permeable bedrock facilitated infiltration, interflow as well as recharge of water tables (regional and perennial). Two levels of detail of soil information namely; Land Type data: level 1 and Observed data: level 2, were used to test the impact of soil information on hydrological modelling. The results were assessed to evaluate the contribution of soil data and the effectiveness of the conceptual model. The contribution of some streamflow generation mechanisms was also calculated. A method for classifying soils based to their hydrological behaviour was proposed. Future research should focus on several aspects (soil water regime, ET, drainage curves, hydraulic conductivity, flowpaths and storage mechanisms) which describe the hydrology of soil of South Africa. Such a system can benefit hydrological modelling, especially in PUBâs.

The use of organic fertiliser as an alternative to inorganic fertiliser increased among subsistence farmers in rural areas in KwaZulu Natal. No clear recommendations exist for the application of different organic fertilisers on vegetables. Two field trials were conducted at Umsunduze Training Centre, KwaZulu Natal during the 2005 and 2006 seasons. The effect of three different organic fertilisers (chicken, kraal manure and compost) were investigated on the growth, yield and quality of cabbage cv. Conquistador and carrots cv. Kuroda. Four application rates were used for each organic fertiliser (chicken manure: 0, 6.25, 12.5 and 25 kg 10 m-2; kraal manure: 0, 12.5, 25 and 50 kg 10 m-2; compost: 0, 25, 50 and 100 kg 10 m-2). Each treatment combination was replicated four times. Organic fertilisers were incorporated into the soil one month before planting. Number of leaves and plant height were measured for the first 8 weeks after planting for both crops. Fresh and dry mass was determined at harvesting for both cabbage and carrots. Cabbage head and carrot shoulder diameter, carrot root length and carrot root total soluble solids were measured at harvesting. Both crops were graded (cabbage into 3 and carrots into 5 classes) according to their external appearance. After harvesting, soil analysis (2005 and 2006) and plant analysis (2006) were done for both crops. Chicken manure applied at 12.5 or 25 kg 10 m-2 showed a significant increase in the growth rate of cabbage during the first 8 weeks after transplanting in both seasons. During 2005, fresh mass of cabbage that received 12.5 or 25 kg 10 m-2 chicken manure was significantly higher and of better quality than the other organic fertiliser treatments. In 2006, the fresh mass and quality of cabbage that received 50 kg 10 m-2 kraal manure, 25 kg 10 m-2 chicken manure or 100 kg 10 m-2 compost was significantly higher than the other organic treatments. Dry mass also significantly increased when 25 kg 10 m-2 chicken manure was applied. Compost significantly increased the nitrogen, phosphorus, potassium, sulphur and calcium content, while kraal manure significantly increased the phosphorus, potassium and magnesium content of the soil after two years of application. It was in most cases the two highest application rates (Rate 2 and 3) that significantly influenced the chemical properties of the soil. Only chicken manure significantly influenced the nitrogen content of cabbage heads. Carrot plants that received chicken and kraal manure at Rate 2 or 3 produced the most number of leaves while the tallest carrot plants were obtained where 25 kg 10 m-2 chicken manure or 50 kg 10 m-2 compost was applied, at 8 weeks after planting. Different organic fertilisers and application rates did not significantly influence the fresh mass and root length of carrots. Dry mass of carrots that received 25 kg 10 m-2 chicken manure, 50 kg 10 m-2 kraal manure or 25 kg 10 m-2 compost was significantly greater than plants that did not receive any fertiliser in 2006. High organic fertiliser rates (Rate 3) significantly increased shoulder diameter. In 2005, chicken manure and compost significantly decreased total soluble solid content of carrots. In 2006, the highest total soluble solid content was obtained with 12.5 kg 10 m-2 chicken manure. An increase in the organic fertiliser rate promoted the development of hairy carrots in 2005 and carrots that received compost (Class 3) was of a poorer quality than those that received chicken or kraal manure (Class 2) in 2006. Compost significantly increased the phosphorus, potassium content and NIRS organic matter of the soil and kraal manure only significantly increased the sulphur content of the soil after two years of application. Chicken manure (25 kg 10 m-2) and 100 kg 10 m-2 compost significantly increased the nitrogen content of carrot roots, while the calcium content was significantly lowered where chicken manure was applied. Kraal manure significantly increased the iron content and 6.25 kg 10 m-2 chicken manure increased the total carbon content of carrots.