Hill Country Pastures Research Articles

The effect of two lime sources on short-term changes in soil pH under Marlborough hill country pasture

The effect of fine slurried lime applied at 200 kg/ha on soil pH at two depths was compared with 400 and 2500 kg/ha of local agricultural (ag) lime in the presence and absence of sulphur (S) superphosphate 20, in Marlborough hill country for one year. In the absence of fertiliser all lime treatments significantly raised soil pH in the top 25 mm for the 355 days after application. Initial responses declined from day 14 or 35 to day 138 before increasing at day 355. Fine lime did not significantly alter pH in the 25-75 mm zone until day 355. The low rate of ag lime significantly raised pH in the 25-75 mm zone for the whole year. The high rate of ag lime significantly increased pH in the top 25 mm over the other lime treatments for the 355 days and over the fine lime treatment in the 25-75 mm zone from day 35. In the presence of fertiliser in the top 25 mm, fine lime significantly increased pH at day 14 only, and low ag lime at day 355 only. The high rate of ag lime significantly increased pH over the control from day 14 and over the other lime rates from day 35. In the 25-75 mm zone the high rate of ag lime significantly increased pH over the control and the low ag lime rate from day 71 but was significantly better than fine lime from day 35. It is likely that rain immediately after application and higher than average annual rainfall hastened the release of fine and intermediate particles of lime. However provided lime meets the accepted criteria for particle size distribution and maximum size it is the rate of application which dictates the magnitude of response. In Marlborough hill country it was 43% cheaper to aerially apply 400 kg/ha of ag lime compared to 200 kg/ha of fine lime with the added benefit of a greater residual effect beyond one year. Keywords: agricultural lime, fine lime, slurry, soil pH

Quantifying the impact of a weed in a perennial ryegrass–white clover pasture

Any plant not sown from seed is often labeled a weed in improved pastures of New Zealand. Most improved pastures are a mix of perennial ryegrass and white clover but generally are infested with broadleaf weeds. Changes in forage production due to individual weeds were determined using measurements of perennial ryegrass and white clover before and after dairy cattle, beef cattle, or sheep grazing under, near, and far from individual plants of six rosette-forming weed species throughout a growing season. The larger weeds, bull thistle and musk thistle, reduced the amount of forage utilized 42 and 72%, respectively, in beef cattle– and sheep-grazed hill-country pastures. Forage production under and near Canada thistle, hedge mustard, broadleaf plantain, and hairy buttercup in a dairy pasture was greater (136, 140, 178, and 450%, respectively) than in the control areas. Although the dairy pasture was grazed following recommended grazing procedures, our results indicate that this grazing system was not maximizing forage yield potentials of perennial ryegrass and white clover and that these weeds served as an indicator that the pasture was being overgrazed.

Nitrate removal in riparian wetlands: interactions between surface flow and soils.

Riparian wetlands containing springs are thought to be ineffective at removing nitrate because contact times between the upwelled ground water and the underlying microbially active soils are short. Tracer experiments using lithium bromide (LiBr) and nitrate (NO3-N) injected at the surface were used to quantify residence times and NO3-N removal in a riparian swale characteristic of New Zealand hill-country pasture. An experimental enclosure was used with collecting trays at the downstream end to measure flow and concentration, shallow wells to measure subsurface concentrations, and an array of logging conductivity probes to monitor tracer continuously. The majority of added tracer reached the outlet more slowly than could be explained by surface flow, but more quickly than could be explained by Darcy seepage flow. There was evidence from the wells of tracer diffusing vertically to a depth of at least 5 cm into the surface soil layer, which was permanently saturated and highly porous. During dry weather 24 +/- 9% of added NO3-N was removed over a distance of 1.5 m largely by denitrification. The net uptake length coefficient for this wetland (K = 0.08 +/- 0.03 m(-1)) is slightly higher than the range (K = 0.01-0.07 m(-1)) measured in a small stream channel infested with macrophytes. Nitrate removal is expected to decrease with increasing flow. Seepage flow is estimated to have removed only 7 +/- 4% of the added NO3-N and we hypothesize that vertical diffusion substantially increases NO3-N removal in this type of wetland. Riparian wetlands with springs and surface flows should not be dismissed as having low NO3-N removal potential without checking whether there is significant vertical mixing.

Plant diversity effects on herbage production and compositional changes in New Zealand hill country pastures

AbstractA small‐plot field experiment on grazed hill country pastures in the North Island of New Zealand was conducted to examine the productivity and compositional characteristics of swards in response to variation in pasture species diversity. The balanced incomplete factorial design incorporated variation in location, slope, soil fertility and combinations of eight plant functional groups (C4 grasses, annual grasses, annual legumes, perennial C3 grasses, perennial legumes, perennial forbs, ryegrass and browntop). Net herbage accumulation and botanical composition were measured at 18 months (spring) and 24 months (autumn) after oversowing following application of a systemic herbicide. Analysis of variance indicated a significant positive relationship between the number of functional groups sown and herbage accumulation of the sown species in spring, but not with total herbage accumulation. Regression analysis showed that herbage accumulation was also affected by the identity of the functional groups. However, the statistical models indicated that pasture productivity was most strongly influenced by site factors. There was a significant negative relationship between both the number and herbage accumulation of unsown species and the number of functional groups sown, indicating a positive relationship between diversity and resistance to invasion by unsown species. A comparison of the vegetation between the plots before and after oversowing showed that those more diverse prior to sowing returned to their initial composition more rapidly, evidence that diverse vegetation was more resilient in the face of disturbance.

Modelling hill country pasture production: a decision tree approach

Decision tree models were applied to predict annual and seasonal pasture production and investigate the interactions between pasture production and environmental and management factors in the North Island hill country. The results showed that spring rainfall was the most important factor influencing annual pasture production, while hill slope was the most important factor influencing spring and winter production. Summer and autumn rainfall were the most important factors influencing summer and autumn production respectively. The decision tree models for annual, spring, summer, autumn and winter pasture production correctly predicted 82%, 71%, 90%, 88% and 90 % of cases in the model validation. By integrating with a geographic information system (GIS), the outputs of these decision tree models can be used as a tool for pasture management in assessing the impacts of alternative phosphorus fertiliser application strategies, or potential climate change, such as summer drought on hill pasture production. This can assist farmers in making decisions such as setting stocking rate and assessing feed supply. Keywords: data mining, decision tree, GIS, hill slope, rainfall

The development of Trichostrongylus colubriformis larvae on a range of herbage species or on plots of differing topographical aspect.

Five "contaminations", where faeces containing Trichostrongylus colubriformis eggs were deposited on pasture and serially recovered, were used to compare the rate of decline of faecal mass and larval development. In the first three contaminations, faeces from a common source were deposited on swards of browntop (Agrostis capillaris cv Grasslands Muster), ryegrass (Lolium perenne cv Grassland Nui), white clover (Trifolium pratense cv Grassland Tahora), or onto bare ground in the late spring, summer or autumn. The last two contaminations were done on the north facing aspect or south facing aspect of hill country pastures in summer and autumn. Number of free-living nematodes (first- and second-stage larvae (L(1) and L(2)) and soil dwelling nematodes) and third stage larvae (L(3)) recovered from faeces were counted. In spring there was a significant (P<0.01) effect of sward type on the mass of faeces remaining, with greatest mass remaining on browntop and ryegrass 28 days later, and less on bare ground and white clover. In summer there were more (P<0.05) faeces remaining on browntop than on other herbages which had little faeces remaining and which did not differ one from another. In autumn there was a rapid decline in faecal mass. All faeces were gone from white clover and ryegrass swards by day 10 and from browntop and bare ground by day 14. The number of free-living nematodes did not differ markedly between seasons, ranging from 5 to 8.5% of eggs deposited. The number of L(3) recovered was low in spring ( approximately 0.4% of eggs deposited) and did not differ between swards. In summer, more (P<0.05) L(3) were recovered from faeces deposited on swards of ryegrass and white clover than from bare ground or browntop. Most L(3) were recovered from days 7 to 14 ( approximately 1.3% of eggs deposited). In the autumn, low numbers of L(3) were recovered from browntop on day 3 and ryegrass on day 7 (0.2% of eggs deposited) with virtually no L(3) recovered from faeces placed on white clover or bare ground. There were significant (P<0.001) effects of aspect on the amount of faecal mass remaining in both summer and autumn with less faeces remaining on the south facing aspect than on the north. This was particularly evident during the summer when virtually all of the faeces were intact on the north facing aspect but only 40% was remaining on the south on day 28. In the autumn, while faeces were completely gone from both aspects by day 28 but there were less (P<0.05) faeces remaining on the south facing aspect from days 3 to 18 than from the north. There was no aspect effect in either season on the number of free-living nematodes recovered which averaged 8-11% of eggs deposited. In both seasons a greater number of L(3) were recovered from faeces on the south facing aspect than on the north, particularly 3-10 days after faecal deposition. In summer the rise in L(3) recovered in faeces was more rapid on south facing aspect than on the north but both attained a maximum level of approximately 4% of eggs deposited. In autumn on day 3 there was a rapid rise on south facing aspect to approximately 21% of eggs deposited followed by a gradual decline on day 10 while on the north facing aspect numbers of L(3) recovered only attained 10% of eggs deposited.

Soil nitrogen mineralisation changes rapidly when pine is planted into herbicide-treated pasture—the first two years of growth

The conversion of hill country pastures to exotic forest plantations has occurred rapidly in New Zealand over the last 10 years. This land-use change affects properties of the mineral soil, especially nitrogen (N) cycling. Here we studied the changes in soil in situ N mineralisation, in leaching, and microbial biomass, when Pinus radiata D. Don is planted into pasture; sheep were used to reduce pasture herbage before planting, and then herbicide was used to control the rank growth of grass around the trees. Total net N mineralisation in soil (0–100 mm) under pasture was 325 kg/ha.year. Net N mineralisation in the herbicide-treated areas was about double that under pasture or rank grass in the first 2 months. The concentration of nitrate-N in soil solution in the herbicide-treated areas was then 81 mg/L, compared with &lt;2 mg/L under pasture. During this time, the pH under the pine trees decreased very rapidly as nitrification increased. Soil nitrification and nitrate leaching were enhanced for 15 months after application of herbicide. After this 15-month period, soil total carbon (C) was slightly lower (P &lt; 0.10) under trees than rank grass, whereas microbial C and N were markedly lowest (P &lt; 0.05) under the trees. Over this period, about 18 kg N/ha was leached to 250 mm in the tree-planted area. The data also give additional insights into processes that occur when soil cores in buried bags are used to estimate N mineralisation.

Farm forestry for economic and environmental sustainability - A new decision support system for farm foresters

The objective of this programme is to provide farm foresters and others with knowledge about sustainable and profitable land use with commercial tree crops. Initially the study examined the role of trees in stabilising soils when planted on eroding hill country pasture. Three species - radiata pine, Douglas-fir, and poplar - were compared for effects in reducing erosion. Tree size, tree stocking per hectare, root tensile strength, and rate of decay of roots after harvest were found to be important. Erosion control becomes effective once a stand of trees reached the equivalent of 30 tonnes/ha of radiata pine root biomass. Silviculture, and choice of species, determines to what extent this critical threshold is achieved. Decision support software, developed in this programme as "calculators', estimate the 'Equivalent Farming Gross Margin' of crops of radiata pine, and Douglas-fir, compared to the livestock previously grazing the land. The calculators, which run under Microsoft EXCELTM, also allow the identification of the most profitable silviculture for the tree crop, and generate yield tables. The calculators are being applied in two case studies; the first involves calibrating the radiata pine calculator for Hawkes Bay and the Wairarapa against actual tree data. Calibration of the calculator for bare land is also being studied. The second study will investigate how well tree crops can compete financially with pastoral farming systems in the Lake Taupo catchment, where there are increasing concerns about nutrient in-flows from pastoral farming. Further enhancements of the calculators are planned which will permit calibration against younger stands, and evaluation of a much wider range of silviculture. Keywords: farm forestry, erosion, root biomass, root strength, financial return, IRR, PNW, farming gross margin, Pinus radiata, Douglas-fir, poplar

Future changes in New Zealands hill country pasture weeds

This paper examines the current and possible future status of weed problems in hill country pastures in New Zealand Factors like lower fertiliser inputs stocking rates rural depopulation and changing land use that have affected pastures and pasture management in recent years were assessed The possible effects of climate change on pastures and weed invasions were also considered In addition farmers Regional Councils chemical companies and other stakeholders were surveyed for their opinions on existing and increasingly important weed problems Survey results indicated a resurgence of woody weeds in hill country probably as a result of lower fertiliser input/stocking rates and changing livestock classes due to marginalisation of hill country farming There were few indications of any new weed species appearing in hill country pastures Suggestions were made for increasing surveillance efforts to assist in the early detection of newly emerging weeds in pastures

Effects of afforestation on organic carbon, nitrogen and sulfur concentrations in New Zealand hill country soils

This paper describes results from a study of the effects of first rotation radiata pine ( Pinus radiata) on major organic constituents (carbon, nitrogen and sulfur) in hill country pasture soils in New Zealand. Soil properties were compared under 17–19-year-old radiata pine and adjacent pasture at four sites on the boundary of a 9000-ha forest. No fertiliser had been applied to either forest or pasture areas since tree establishment, and the pasture sites were either ungrazed or lightly grazed. Differences between sites included soil type (influenced mainly by drainage) and soil fertility (influenced mainly by fertiliser history prior to afforestation). Concentrations of organic carbon and nitrogen were 15–43% lower in soil to a 12–18-cm depth under trees compared with pasture at three sites. On the other hand, total (organic) sulfur was significantly lower (19–44%) in topsoil under trees compared with pasture at all sites, while concentrations of plant available sulfate–sulfur were consistently and significantly higher in soil to 30-cm depth under trees compared with pasture. These findings confirmed that afforestation of hill country pasture soils resulted in net mineralization of soil organic sulfur in addition to organic carbon and nitrogen.

Effect of cattle treading on interrill erosion from hill pasture: modelling concepts and analysis of rainfall simulator data

Damage to pasture as a result of intensive grazing and treading by cattle increases the erosion of sediment and associated nutrients. In this study we present a model for the effect of treading damage on interrill erosion. The model formulation is based on the interrill erosion components of conventional process-based erosion models, with some modifications. The model was developed using data from small rainfall simulator plots (0.5 m2) on hill-country pasture in New Zealand with varying amounts of treading damage. Treading increased the amount of bare ground, and this resulted in increased concentrations of sediment in runoff. Concentration was found to increase linearly with the amount of bare ground. Treading resulted in increased runoff, which had some effect on sediment concentration for the high runoff rates in the experiments, but would have a negligible effect on concentration for typical natural runoff rates. However, the increased runoff results in greater sediment loads because a larger volume of sediment-laden runoff is produced. The increase in runoff was modelled through a reduction factor for the hydraulic conductivity which varied linearly with the fraction of damaged ground. For 100% damaged ground the hydraulic conductivity was approximately halved. The recovery of bare ground and damaged ground over time after treading was also assessed. Bare ground resulting from treading typically halved after 2 months, while damage took longer to recover. Such treading-related effects are superimposed on seasonal variations in erodibility, bare ground, and infiltration capacity. Based on the results of the study, some measures to reduce treading-related erosion are suggested.

Resident pasture growth and the micro-environment beneath young, widespaced poplars in New Zealand

Poplar (Populus spp.) trees are planted on pastoral hill country throughout New Zealand, primarily for soil conservation. The effect of wide-spaced trees (16-100/ha) aged 8-15 years on understorey pasture growth, botanical composition, and microenvironmental characteristics, was determined at Pohangina (1997-2000) and Lawrence (1998- 2000) in the lower North and South Islands, respectively. Relative to environments without trees, at Lawrence pasture growth (13 100 kg dry matter (DM)/ha/yr) was reduced by 20% and 34% on north and south sides of trees, respectively. At Pohangina (7915 kg DM/ha/yr), trees had less influence (7% and 14% reduction) on understorey pasture growth. There were also strong seasonal effects at both sites, corresponding to when the trees were foliated. Swards at each site comprised 81-93% grass. At Lawrence, swards had similar botanical composition beneath and beyond trees. Swards on the north side of trees at Pohangina comprised relatively high grass and low legume content compared with those on the south side and in the open. Compared with open pasture, areas beneath young poplars received up to 24% less rainfall and 31% less solar irradiance, and soil water content (0-200 mm depth) was up to 33% lower in summer and autumn. At intermediate soil water contents (0.25-0.35 m3/m3), the profile of soil water content around trees during drying was frequently U-shaped, being lowest beneath the stem and increasing with distance away from the tree. Likely reasons for the pasture responses and variation in tree-pasture interactions between sites are discussed. The results will be used to model changes in tree-pasture interactions over time. Keywords: agroforestry, poplar, Populus, silvopastoralism, soil conservation, soil water, treepasture interactions

Factors influencing the contribution of narrow-leaved plantain to North Island hill country pastures

We examined the contribution of narrow-leaved plantain (Plantago lanceolata) to pasture production and composition, as part of a larger experiment evaluating the role of biodiversity in North Island hill country pastures. Plantain was sown at rates between 0 and 13.5 kg/ha (equivalent) into small plots at two sites representative of North Island hill country pastures - Whatawhata and Ballantrae Research Centres. The sites encompassed variation in both slope and soil fertility. We measured the abundance and percent composition of plantain, and the total yield of the herbage growing on the plots in the spring and autumn of the year following establishment. The average abundance of plantain in both spring and autumn was greater on higher fertility plots but was not different between easy and steep slopes. Abundance was also related to sowing rate and the contribution of plantain to harvested DM yield was strongly related to abundance. There was some evidence that the percentage of plantain in spring pastures was positively related to total plot yield. Given that plantain occurs ubiquitously in most pastures, contributing 2-8% of pasture productivity, the data indicated a sowing rate of approximately 1 kg/ha was a minimum to significantly increase the abundance and contribution to productivity of this species. Keywords: biodiversity, hill country, pasture, plaintain

Poplars and willows for soil erosion control in New Zealand

Poplars ( Populus) and willows ( Salix) are exotic to New Zealand and have been introduced and cultivated over the last 160 years, for soil erosion control on pastoral hill country, riverbank protection, shade, windbreaks and woodlot forestry. During the 1960s and 1970s over two million poplars were planted in government-subsidised erosion control schemes. Planting techniques and patterns are discussed. This type of subsidised planting declined in the late 1980s and 1990s with the emphasis shifting to land management systems incorporating Radiata pine ( Pinus radiata) afforestation, poplar silvipastoral systems, and various plant combinations including poplars and willows for riparian management. To prevent long-term degradation by soil erosion, there is a need to develop economic silvipastoral systems on at least one million hectares of New Zealand pastoral lands and the New Zealand research effort is refocusing on obtaining the necessary information to ensure this is a viable option for farmers.

Invasion of sheep dung by nematophagous fungi and soil nematodes on a hill country pasture in New Zealand

Subsamples of sheep dung placed on plots on a hill country farm in New Zealand were recovered at intervals after placement in summer (January) and autumn (April) and examined for the presence of soil, nematodes and fungi which parasitise nematodes (nematophagous fungi). At 8 d after placement in January, 35% of dung samples contained nematophagous fungi, with 72% of samples infested at 32 d. Harposporium bysmatosporum, a species similar to H. helicoides, Monacrosporium candidum and Nematoctonus spp. occurred most frequently at this time. At 1 d after placement in April, 36% of samples contained nematophagous fungi, with 63% of samples infested by 8 d. The most prevalent species at this time were the H. helicoides-like sp., M. candidum and Verticillium balanoides. Dung on all plots contained soil nematodes by 4 d after placement in January and 1 d after placement in April.

Soil and solution chemistry under pasture and radiata pine in New Zealand

The conversion of hill country pasture to exotic forest plantations is occurring rapidly (70,000 ha yr−1) in New Zealand. Impacts of this land-use change on soil properties, soil fertility, and water quality are only beginning to be investigated. This study examines the effects of radiata pine (Pinus radiata) on soil and soil solution chemistry, in a region of low atmospheric pollution, 20 years after plantation establishment, assuming that the pasture and pine research sites had comparable soil properties before planting pine. The primary effects of conversion on soil chemistry were a decrease of organic carbon in the mineral soil that was balanced by an accumulation of the surface litter layer, a decrease in soil N, soil acidification, and increased pools of exchangeable Mg, K, and Na. Soil solution studies revealed a large input of sea salts by enhanced canopy capture of sea salts that contributed to much larger solute concentrations and elemental fluxes in the pine soil. Sea salts appear to accumulate in the micropores of pine soil during the dry summer period and are slowly released to macropore flow during the rainy season. This results in a progressive decrease in solute concentrations over the period of active leaching. While chloride originating from sea salt deposition was the dominant anion in the pine soil, bicarbonate originating from root and microbial respiration was the dominant anion in the pasture soil. Carbon dioxide concentrations in the soil atmosphere were 12.5-fold greater in the pasture soil than in the pine soil due to greater rates of root and microbial respiration and to slower diffusion rates resulting from wetter soil conditions in the pasture. Although elemental fluxes from the upper 20 cm of the soil profile were substantially greater in the pine soil, these losses were compensated for by increased elemental inputs resulting from nutrient cycling and enhanced canopy capture of sea salts.

Long-term effects of pastoral fallowing on the distribution and performance of white clover (Trifolium repens L.) in a hill country pasture

Previous work found that white clover (Trifolium repens L.) yield initially decreased, but subsequently increased following a pastoral fallow. The objective of this research was to quantify the response in herbage production and stolon characteristics of white clover up to 4 years after fallowing. Four treatments were used: fallowed 1990/91 (F4), fallowed 1991/92 (F3), fallowed 1993/94 (F1) and non-fallowed (F0). The fallowing period was between September and May. White clover dry matter yield (between 15/12/94 and 18/5/95) was significantly greater for the treatment F4 than F0 (P

Development of subterranean clover(Trifolium subterraneumL.) genotypes for New Zealand pastures 2. Wairakei persistence evaluation

Abstract A 3‐year trial to evaluate the persistence of a number of selected subterranean clover (Trifolium subterraneum L.) lines and cultivars was carried out in grazed pastures in hill country of the central North Island, New Zealand. Seedlings were transplanted into existing swards on an easy (10–15° slope) contoured paddock. Spring cover, summer/autumn seedling emergence, and winter plant populations were measured, focussing on annual regeneration of the lines. Important factors in the success of subterranean clover genotypes were identified as late maturity and strong autumn regeneration. The recent cultivar ‘Karridale’ outperformed the well‐adapted ‘Tallarook’. Five other lines evaluated in this trial stood out in terms of successful persistence and the ability to make a substantial contribution to late winter/spring pasture growth. All had the ability to consistently regenerate winter plant populations in excess of 300 plants/ m2, and accumulate buried seed reserves of over 1000 seeds/m2. These lines were therefore considered suitable for further development towards a well‐adapted cultivar for New Zealand summer‐dry hill country pastures.

Allozyme variation within and between three populations of browntop(Agrostis capillaris)

Abstract Allozyme variation in the tetraploid browntop (Agrostis capillaris) cultivar ‘Grasslands Muster’, and two resident hill country browntop populations was investigated. The aim was to develop a set of genetic markers that would allow this cultivar to be reliably distinguished from the resident populations, enabling persistence of this cultivar in hill country pastures to be monitored following oversowing. Screening of 17 enzyme systems yielded three polymorphic loci: Gpi; Pgm; and Mdh. For Gpi, 12 alleles were found among the three populations sampled, allele frequencies ranging from 0 to 0.245. Pgm showed six alleles, and frequencies ranged from 0 to 0.792. Mdh could only be analysed in terms of phenotype frequencies, and four phenotypes were recognised, with frequencies ranging from 0 to 0.6. Pairwise G‐tests and the calculation of geometric distances between the populations on the basis of this data suggested that allele frequencies at the loci Gpi and Pgm differ sufficiently between ‘Grasslands...

Use of capital fertiliser and lime to improve pasture production in Northland

Previous research in Northland identified the requirements for phosphate and lime in pasture development. Large capital inputs were necessary (1.8-2.0 t superphosphate and 2.5-5 t lime/ha in the first 12-18 months). More recently (1990-1993) three trials have been conducted on typical unimproved or improved hill country pasture in Northland to investigate lime (rates and frequencies) and phosphate (rates and forms) requirements. Results show that capital inputs of both fertiliser and lime are still very necessary in Northland. Marked responses occurred in the trials, with an average 40% increase to P and 16% increase to lime. The need for a soluble fertiliser like superphosphate was highlighted. In practice the aim must be to get as much of the potentially high producing land as possible into the soil test ranges for maximising pasture production. Improvement programmes need to be tailored to the individual farm. In dairying, improvement programmes can be completed relatively quickly (l-2 years) given the current economic situation, but in hill country the programme must of necessity be longer term (4-5 years). Emphasis must first be on developing the land with the highest potential. In time, areas with lower productive potential can also be considered for improvement, although alternative sustainable land use options should also be considered. Keywords: capital inputs, fertilisers, lime, optimum soil tests, phosphate, soil fertility