Combining deliberative and computer-based methods for multi-objective land-use planning

This paper reports the outcomes of a deliberative workshop comparing land-use plans proposed by land-manager or domain experts with those derived using a computer-based decision support system (DSS). The DSS integrates four main components, a geographic information system, land-use systems simulation models, impact assessments and land-use planning tools. The land-use planning tools draw on the other components to generate and evaluate alternative patterns of land use and management. Since the land-use planning tools are based on multi-objective genetic algorithms (mGAs) it is possible to generate a range of alternative plans that define the structure of the trade-off between the objectives. The workshop tasked the delegates with specifying land-use plans that achieved the best compromise between two objectives known to be non-commensurable and conflicting. The nature of the best compromise was dependent on their individual perspectives. The delegates proposed allocations both as individuals and in researcher-facilitated sub-groups. The mGA allocations were then compared with those derived by delegates and were found to be broadly similar in performance. Differences in the range of allocations considered feasible were explained by the hard and soft constraints on allocations agreed between the delegates and articulated within the workshop process. The hypothesis that part of the difference in performance between the mGA and delegate allocations was due to the delegates blocking together fields with the same land use for convenience of management was proved. The analysis of the group allocations revealed that the decision-making process had failed to improve on the individual allocations. From these results it was concluded that there was a potential role for mGA based land-use planning tools in researching into, and deliberating on, the possible impacts of policy or other factors affecting land-use systems. It was further concluded that the tools should not be used in isolation since there was the need for stake-holder inputs to adequately define the range of feasible and practical land-use plans.     

A conceptual approach to the modelling of herbage intake by hill sheep

A modelling approach is examined as a method of investigating alternative management strategies for improved systems of hill sheep production. In order to take account of the wide range in the quality of hill herbage and the ability of the hill sheep to select preferred components, herbage has been conceptually classified in terms of its digestibility; the digestibility classes are then grazed selectively by sheep. The model deals with herbage growth and deterioration, diet selection and the maintenance and liveweight change of wether sheep. Results produced by the model, in which wethers grazed Agrostis-Festuca at two stocking rates, are discussed.     

The implications of controlling grazed sward height for the operation and productivity of upland sheep systems in the UK. 4. The effect of seasonal pattern of nitrogen fertilizer application and annual stocking rate

Greyface (Border Leicester × Scottish Blackface) ewes, mated in October, were housed in winter and turned out after lambing in late March to one of four treatments replicated three times on perennial ryegrass (Lolium perenne)-dominated pastures. On three of the treatments the stocking rate was 12·5 ewes plus lambs ha^?1 annum^?1 (SR_12·5), whereas on the fourth it was 15·0 ewes plus lambs ha^?1 annum^?1 (SR_15·0). There were two levels of applied fertilizer nitrogen (N), 152 kg N ha^?1 annum^?1 (N₁₅₂) and 205 kg N ha^?1 annum^?1 (N₂₀₅). Three patterns of nitrogen application were used: predominantly in spring (E), predominantly in autumn (L), and mainly in spring and autumn (E + L). Grazed sward surface height was controlled within the range 3·5–5·5 cm during spring and summer, and supplementary feed was offered when sward height was below 3·5 cm. The effects on animal performance, yield of silage and requirement for supplementary feed were measured over 3 years (1986–88). Management of the sward height within the specified limits resulted in similar levels of individual animal performance for all treatments, but treatment SR_15·0N₂₀₅E + L produced a significantly (P < 0·05) greater output of lamb per hectare. There was no evidence to suggest that, by increasing the amount of N fertilizer applied in the autumn, ewe reproductive performance was increased. Neither the treatment with the lower level of N applied in the spring (SR_12·5N₁₅₂L) nor the high stocking rate treatment (SR_15·0N₂₀₅E + L) was self-sufficient in winter feed (silage) production. SR_15·0N₂₀₅E + L also required more supplementary feed in both the lactation (38·1 kg ewe^?1) and the mating (9·1 kg ewe^?1) periods. SR_12·5N₁₅₂L required the second greatest amount of supplementary feed during lactation (36·1 kg ewe^?1), whereas SR_12·5N₂₀₅E + L required the least supplementary feed over both periods (27·8 kg and 4·8 kg ewe^?1). Taking all treatments together, there were significant (P < 0·05) differences between years in lamb weaning weight (kg), lamb output (kg ha^?1), yield of silage (kg ewe^?1) and supplementary feed required (kg ewe^?1), arising mainly from a lower level of herbage production in one year. Treatment SR_12·5N₁₅₂E generated the highest gross margin per hectare.     

The implications of controlling grazed sward height for the operation and productivity of upland sheep systems in the UK. 5. The effect of stocking rate and reduced levels of nitrogen fertilizer

The implications for UK upland sheep systems of reducing nitrogen fertilizer application to perennial ryegrass/white clover swards were studied over 3 years. Sward height (3·5–5·5 cm) was controlled for ewes with lambs until weaning using surplus pasture areas for silage; thereafter, ewes and weaned lambs were grazed on separate areas, and sward height was controlled by adjusting the size of the areas grazed and using surplus pasture areas for silage if necessary. Combinations from three stocking rates [10, 6 and 4 ewes ha⁻¹ on the total area (grazed and ensiled)] and four nitrogen fertilizer levels (150, 100, 50 and 0 kg ha⁻¹) provided six treatments that were replicated three times. Average white clover content was negatively correlated with level of nitrogen fertilizer. The proportion of white clover in the swards increased over the duration of the experiment. Control of sward height and the contribution from white clover resulted in similar levels of lamb liveweight gain on all treatments. All treatments provided adequate winter fodder as silage. It is concluded that the application of nitrogen fertilizer can be reduced or removed from upland sheep pastures without compromising individual animal performance provided that white clover content and sward height are maintained. Resting pastures from grazing by changing ensiled and grazed areas from year to year sustained white clover content over a 3-year period.     

Characterization of Prunus domestica L. in vitro regeneration via hypocotyls

Several important aspects of regeneration of European plum from hypocotyl explants were studied. Multiple shoots were induced and full plants were recovered for a large number of plum varieties. This indicates that European plum species is, in general, very responsive to in vitro regeneration from hypocotyls. Shoot organogenesis could be induced from both mature and immature seed explants but regeneration efficiency was higher when immature seeds were used. Rooting efficiency for varieties with low rooting tendency could be greatly increased by addition of naphthaleneacetic acid in the medium. Primary shoots, when sub-cultured on fresh induction medium, produced multiple shoots at a high frequency and such multiplication could continue for many cycles. The secondary new shoots could be induced for various plum varieties. Plant recovery from the secondary shoots was as efficient as that from the primary shoots. This new system may be an alternative for plum transformation with a potential for increasing transformation efficiency. The system can be used for propagation of transgenic lines and other genetic clones of various varieties.     

Integration of forestry and agriculture—A model

This paper describes a modelling approach to the allocation of land as between forestry and agriculture in the context of hill and upland. The model can be used to examine objectively the outcome of some of the stated objectives and constraints concerned with integration. Examples in the use of the model are presented.     

The contribution of anorexia to reduced growth in zinc‐deficient chickens

1. It was shown, using a paired‐feeding technique, that the growth depression in zinc‐deficient chicks was largely caused by the greatly reduced consumption of the deficient diet.

2. Chicks receiving a zinc sulphate solution directly into the crop ate an amount of zinc‐deficient diet similar to that of the zinc‐sufficient diet eaten by the control chicks; palatability was thus ruled out as the cause of the anorexia.

3. Only chicks receiving the zinc‐deficient diet displayed signs of zinc deficiency.     

The implications of controlling grazed sward height for the operation and productivity of upland sheep systems in the UK. 3. The effect of choice of genotype, level of nitrogen fertilizer and lamb:ewe ratio

Grazed sward surface height was controlled within the range 3·25–4·75 cm during spring and summer in two experiments. In Experiment 1, the effects of stocking two breeds of ewe of similar size but different potential levels of reproductive performance [Brecknock Cheviot (C) and Beulah Speckled Face (B)] at different annual stocking rates of twelve (SR₁₂) and twenty (SR₂₀) per hectare, rates of nitrogen fertilizer of 100 (N₁₀₀) and 200 (N₂₀₀) kg N ha^?1 annum^?1 and different lamb:ewe ratios (C_1·2, B_1·2 and B_1·5) were measured in four treatments (SR₂₀N₂₀₀C_1·2; SR₂₀N₂₀₀B_1·2; SR₂₀N₂₀₀B_1·5; SR₁₂N₁₀₀C_1·2) replicated three times. In each of three years animal performance and yield of silage from areas of pasture surplus to grazing requirements were measured. In Experiment 2, breed B was compared with the Welsh Mule (W) breed, a larger with a higher potential reproductive performance, at two stocking rates, two rates of nitrogen fertilizer and two lamb:ewe ratios set on the basis of results from Experiment 1 (SR₁₈N₂₀₀B_1·5; SR₁₂N₁₀₀B_1·5; SR₁₈N₂₀₀W_1·5; SR₁₈N₂₀₀W_1·7). The treatments were replicated three times. The same terminal sire (Suffolk) was used in both experiments. A primary aim of the experiments was to test the validity of the experimental procedures used for comparing breeds of sheep where nutrition is provided predominately from grazed pastures. In Experiment 1, there was no difference between breeds C and B in the live weights of individual lambs at weaning at the same SR (20), N rate (200) and lamb:ewe ratio (1·2). Breeds C and B produced similar total yields of lamb (633 kg lamb ha^?1± 10·5) and silage (193 kg DM ewe^?1± 37·7), but breed B had a higher level of potential reproductive performance (1·59 vs. 1·37 lambs ewe^?1: P < 0·001). The treatments SR₂₀N₂₀₀B_1·5 and SR₁₂N₁₀₀C_1·2 produced, respectively, greater and lesser yields of lamb (725 vs. 384 kg lamb ha^?1, P < 0·001) and lesser and greater yields of silage (123 vs. 327 kg DM ewe^?1, P < 0·001). In Experiment 2, the live weight of lambs at weaning from breed W were heavier than from breed B (29·1 vs. 26·2 kg lamb^?1, P < 0·01) but there was no significant difference in total yield of lamb weaned between breeds W and B at the same SR (18), N rate (200) and lamb:ewe ratio (1·5) (747 kg lamb ha^?1± 19·2), or in the yield of silage (66 kg DM ewe^?1± 16·4), but breed W had a higher potential reproductive performance (1·85 vs. 1·58 lambs ewe^?1, P < 0·05). The treatments SR₁₈N₂₀₀W_1·7 and SR₁₂N₁₀₀B_1·5 produced, respectively, greater and lesser yields of lamb (840 vs. 473 kg lamb ha^?1, P < 0·001) and similar and greater yields of silage (60 vs. 141 kg DM ewe^?1, P < 0·05). The experimental approach adopted and the management protocols used provided a basis for ranking the performance of the breeds of ewes examined at appropriate levels of annual stocking rate, N-fertilizer input and lamb:ewe ratio.     

The implications of controlling grazed sward height for the operation and productivity of upland sheep systems in the UK: 7. Sustainability of white clover in grass/clover swards with reduced levels of fertilizer nitrogen

The sustainability of white clover in grass/clover swards of an upland sheep system, which included silage making, was studied over 5 years for four nitrogen fertilizer rates [0 (N₀), 50 (N₅₀), 100 (N₁₀₀) and 150 (N₁₅₀) kg N ha^?1]. A common stocking rate of 6 ewes ha^?1 was used at all rates of N fertilizer with additional stocking rates at the N₀ fertilizer rate of 4 ewes ha^?1 and at the N₁₅₀ fertilizer rate of 10 ewes ha^?1. Grazed sward height was controlled, for ewes with their lambs, from spring until weaning in late summer by adjusting the proportions of the total area to be grazed in response to changes in herbage growth; surplus pasture areas were harvested for silage. Thereafter sward height was controlled on separate areas for ewes and weaned lambs. Areas of pasture continuously grazed in one year were used to make silage in the next year. For treatments N₀ and N₁₅₀, white clover stolon densities (s.e.m.) were 7670 (205·4) and 2296 (99·8) cm m^?2, growing point densities were 4459 (148·9) and 1584 (76·0) m^?2 and growing point densities per unit length of stolon were 0·71 (0·015) and 0·67 (0·026) cm^?1 respectively, while grass tiller densities were 13 765 (209·1) and 18 825 (269·9) m^?2 for treatments N₀ and N₁₅₀ respectively. White clover stolon density increased over the first year from 780 (91·7) cm m^?2 and was maintained thereafter until year 5, reaching 8234 (814·3) and 2787 (570·8) cm m^?2 for treatments N₀ and N₁₅₀ respectively. Growing point density of white clover increased on treatment N₀ from 705 (123·1) m^?2 to 2734 (260·7) m^?2 in year 5 and it returned to the initial level on treatment N₁₅₀ having peaked in the intermediate years. Stolon density of white clover was maintained when the management involved the annual interchange of continuously grazed and ensiled areas. The non‐grazing period during ensiling reduced grass tiller density during the late spring and summer, when white clover has the most competitive advantage in relation to grass. The increase in stolon length of white clover in this period appears to compensate for the loss of stolon during periods when the sward is grazed and over winter when white clover is at a competitive disadvantage in relation to grass. The implications for the management of sheep systems and the sustainability of white clover are discussed.     

The implications of controlling grazed sward height for the operation and productivity of upland sheep systems in the UK: 6. The effect of reducing stocking rate and application of fertilizer nitrogen in Wales

Abstract The implications for the agricultural productivity of the UK upland sheep systems of reducing nitrogen fertilizer application and lowering stocking rates on perennial ryegrass/white clover swards were studied over 4 years at a site in Wales. The system involved grazing ewes and lambs from birth to weaning on swards maintained at a constant height with surplus herbage made into silage, thereafter ewes and weaned lambs grazed on separate areas until the onset of winter with adjustments to the size of the areas grazed and utilizing surplus pasture areas for silage. Four stocking rates [SR 18, 15, 12 and 9 ewes ha^?1 on the total area (grazed and ensiled)] and two levels of annual nitrogen fertilizer application (N 200 and 50 kg ha^?1) were studied in five treatments (N200/SR18, N200/SR15, N50/SR15, N50/SR12 and N50/SR9). Average white clover content was negatively correlated with the level of annual nitrogen fertilizer application. White clover content of the swards was maintained over the duration of the experiment with an increasing proportion of clover in the swards receiving 50 kg N ha^?1. Control of sward height and the contribution from white clover resulted in similar levels of lamb liveweight gain from birth to weaning in all treatments but fewer lambs reached the slaughter live weight by September at the higher stocking rates and with the lower level of fertilizer application. Three of the five treatments provided adequate winter fodder as silage (N200/SR15, N50/SR12 and N50/SR9). Because of the failure to make adequate winter fodder and the failure of white clover to fully compensate for reduction in nitrogen fertilizer application, it is concluded that nitrogen fertilizer can only be reduced on upland sheep pastures if accompanied by reduced stocking rates.