Investigating the effects of crop type, fertility management and crop protection on the activity of beneficial invertebrates in an extensive farm management comparison trial

The activity of 11 groups of invertebrates, mainly predators and parasites, was investigated in 2005 and 2006 in a plot trial system on a farm in northern England, where the effects of organic and conventional fertility and crop protection management were separated within different crop types. Invertebrate activity was assessed using pitfall traps and suction sampling. Mixed effects models indicated that crop type significantly affected activity in all 11 groups. Crop protection applications had only a limited impact on activity but fertility management had considerable effects in some crops. Most differences were in barley, wheat and grass/clover, with less in vegetable and bean plots. Carabidae, Lycosidae, Staphylinidae, Linyphiidae and Braconidae gave consistent responses to fertility management, with more activity of the first two groups in organic plots and more of the other three in conventional plots. However, Coccinellidae and Ichneumonidae were not consistent in their activity between crops. After the effects of crop type had been partialled out, a constrained ordination showed that the novel combination of organic fertility and conventional crop protection had the most influence on group activity, with the combination of organic fertility and organic crop protection also significant. Maximising the activity of beneficial invertebrates in organic and sustainable farming systems requires a basic understanding of the effects of both crop type and fertility management, as well as crop protection.     

Density‐dependent and ‐independent effects on the joint use of space by predators and prey in terrestrial arthropod food‐webs

The spatial distribution of predators and their prey is affected by their joint use of space. While the formation of such spatial patterns may be driven by density‐dependent and ‐independent factors our knowledge on the contribution of different land‐use activities on the formation of spatial patterns between predators and prey remains very limited. Agriculture is one of the most prevailing land‐use activities with strong effects on invertebrate densities and structural habitat conditions. Here, we used replicated conventionally and organically managed winter wheat fields to investigate the effects of agricultural land‐use on the spatial patterns of generalist predators and decomposer prey. We then identified the explanatory power of density‐dependent (prey and predator activity density) and density‐independent (vegetation structure) predictors for the observed spatial patterns. Generalist predators were regularly distributed only in conventionally managed fields and this pattern intensified with decreasing Collembola prey availability and increasing spider activity density. Segregation between carabid and spider predators was strongest in fields with lowest wheat plant height, suggesting more intense intraguild interactions in structurally less complex habitats. Collembola were aggregated independent of management and aggregation was strongest in fields with highest Collembola and carabid activity density. Spiders and Collembola prey were associated, but higher aphid densities under conventional management weakened or interrupted this spatial relationship. We conclude that active control of crop plant physiognomy by growth hormones and herbicides in conventionally managed fields promotes predator–predator segregation and that a high availability of aphid prey seems to decouple predator–Collembola prey associations. Our results emphasise the need for a more mechanistic understanding of the effects of land‐use on the formation of spatial patterns and species interactions, especially under scenarios of environmental change and an ongoing loss of biodiversity.     

A comparison of management options for leatherjacket populations in organic crop rotations using mathematical models

1 Pest management in organic systems is challenged by the paucity of options for direct interventions to control damaging populations compared with conventional agriculture. Consequently, a greater emphasis has to be placed on managing pest numbers through a rotation. In the present study, simulation modelling is used to evaluate the effects of different management options on populations of Tipula paludosa (leatherjackets) in organic rotations.
2 The growth of leatherjacket populations in grass was simulated over 5 years for different starting numbers. A significant risk of leatherjacket attack to subsequent crops can be avoided by limiting the fertility building phase of a rotation to a maximum of 2 years.
3 The effect of cultural control through additional cultivation interventions was compared in rotations comprising a grass/clover fertility building phase with host and/or nonhost crops. It is concluded that the effects are marginal and that prophylactic use cannot be recommended.
4 The prophylactic use of biological control agents in permanent grass and grass/arable rotations was investigated. Maximum population reductions in grass were achieved through annual autumn applications but the optimal economic strategy was less frequent than this. Application in the autumn preceding a spring-sown arable crop provided the best risk reduction.
5 A model decision support system for the control of pests in organic systems using data for leatherjacket damage to spring barley is presented. Economic threshold concepts are used to define when cultural control (as additional cultivation) and biocontrol applications should be used.
6 The present study shows the potential benefits of simulation modelling for the rapid evaluation of a wide range of pest management options. Any conclusions drawn from such simulations, however, are provisional until they can be tested experimentally.     

Synthetic host volatiles increase efficacy of trap cropping for management of Colorado potato beetle, Leptinotarsa decemlineata (Say)

Abstract 1 The attractiveness of pitfall traps baited with a synthetic host volatile attractant to colonizing adult Colorado potato beetle, Leptinotarsa decemlineata (Say) was evaluated in a field setting. 2 Significantly more postdiapause, colonizing adult L. decemlineata were captured in baited than unbaited pitfall traps. 3 The potential for this synthetic kairomone to enhance the efficacy of trap cropping as a management tool was evaluated by comparing conventionally managed plots with like‐sized plots bordered by either attractant‐treated trap crop or untreated trap crop. 4 More postdiapause, colonizing adults, egg masses and small larvae were present in attractant‐treated trap crops than in untreated trap crops. 5 There were no significant differences in egg mass and small larvae densities between plots bordered by attractant‐treated trap crops and conventionally managed plots, but there were significantly fewer large larvae and adult beetles in conventionally managed plots. 6 Plant canopy area of conventionally managed plots was significantly greater than in plots bordered by either type of trap crop. 7 Yields for conventionally managed plots and plots bordered by attractant‐treated trap crops did not differ, and less insecticide (44%) was applied to plots bordered by attractant‐treated trap crops.     

Ground beetles (Coleoptera,Carabidae) as indicators of change and pattern in the agroecosystem: Longer surveys improve understanding

Investigations concerned with ground beetle (Carabidae) dynamics in the agroecosystem have generally been limited to relatively short time periods in one crop, commonly wheat, whilst other studies have concentrated on the influence of landscape structure and non-crop habitat on beetle activity, again usually in one crop. Results of a seven-year survey at Nafferton in northern England, with recording from all crops in an organic rotation and from three types of field boundary, indicated that the lack of field boundary management had the greatest influence on ground beetle activity/density in this particular agroecosystem. However, within the crop rotation, grass/clover limited activity/density compared with that in cereal, potato and bean crops and there were also differences within cereal crops. Data from a 17-year survey at Drayton Environmental Change Network (ECN) site in midland England indicate that previous understanding of ground beetle activity and distribution in intensively managed landscapes may have been limited by temporal constraints. At Drayton, changes in surrounding crop cover, with the introduction of willow coppice and reduced area of arable land and agricultural inputs, considerably influenced ground beetle activity/density and assemblages in non-crop habitat. Small, active species dominating the assemblage in the first few years of the Drayton survey were gradually replaced by larger, non-flying species, especially after all the willow coppice had been planted. In both surveys, activity/density of ground beetles was related to disturbance, affecting vegetation cover and structure, but at the field scale at Nafferton and at the farm scale at Drayton. Longer surveys in a variety of landscapes such as those by the United Kingdom Environmental Change Network are likely to improve understanding of activity, diversity and distribution of invertebrates, which are fundamental requirements if predators such as ground beetles are required for ecosystem service provision.     

Generalist predators in organically and conventionally managed grass‐clover fields: implications for conservation biological control

Organically managed agroecosystems rely in part on biological control to prevent pest outbreaks. Generalist predators (Araneae, Carabidae and Staphylinidae) are a major component of the natural enemy community in agroecosystems. We assessed the seasonal dynamics of major generalist predator groups in conventionally and organically managed grass–clover fields that primarily differed by fertilisation strategy. We further established an experiment, manipulating the abundant wolf spider genus Pardosa, to identify the importance of these predators for herbivore suppression in the same system and growth period. Organic management significantly enhanced ground‐active spider numbers early and late in the growing season, with potentially positive effects of plant cover and non‐pest decomposer prey. However, enhancing spider numbers in the field experiment did not improve biological control in organically managed grass–clover fields. Similar to the survey results, reduced densities of Pardosa had no short‐term effect on any prey taxa; however, spider guild structure changed in response to Pardosa manipulation. In the presence of fewer Pardosa, other ground‐running spiders were more abundant; therefore, their impact on herbivore numbers may have been elevated, possibly cancelling increases in herbivore numbers because of reduced predation by Pardosa. Our results indicate positive effects of organic farming on spider activity density; however, our survey data and the predator manipulation experiment failed to find evidence that ground‐running spiders reduced herbivore numbers. We therefore suggest that a positive impact of organic fertilisers on wolf spiders in grass–clover agroecosystems may not necessarily improve biological control when compared with conventional farming.     

Diversity and activity of free-living nitrogen-fixing bacteria and total bacteria in organic and conventionally managed soils

Agricultural soils are heterogeneous environments in which conditions affecting microbial growth and diversity fluctuate widely in space and time. In this study, the molecular ecology of the total bacterial and free-living nitrogen-fixing communities in soils from the Nafferton Factorial Systems Comparison (NFSC) study in northeast England were examined. The field experiment was factorial in design, with organic versus conventional crop rotation, crop protection, and fertility management factors. Soils were sampled on three dates (March, June, and September) in 2007. Total RNA was extracted from all soil samples and reverse transcribed. Denaturing gradient gel electrophoresis (DGGE) and quantitative PCR (qPCR) were used to analyze nifH and 16S rRNA genes in order to study free-living diazotrophs and the total bacterial community, respectively. Crop rotation was shown to have a significant effect on total bacterial diversity (and that of free-living N fixers) (P ≤ 0.001). On all three dates, nifH activity was higher in the conventional crop rotation. In contrast, qPCR analysis of free-living N fixers indicated significantly higher levels of activity in conventionally fertilized plots in June (P = 0.0324) and in plots with organic crop protection in September (P = 0.0143). To our knowledge, the effects of organic and conventional farming systems on free-living diazotrophs have never been studied. An increased understanding of the impacts of management practices on free-living N fixers could allow modifications in soil management practices to optimize the activity of these organisms.     

陕西渭北柿子园种植白三叶草对土壤养分和生物学性质的影响

种植豆科绿肥可以有效增加氮肥来源,提高水土保持能力,改善生态环境与土壤质量,是促进农业生产可持续发展的重要措施之一.本试验研究了柿子园种植白三叶草对土壤养分和生物学性质的影响,以探明果园种植豆科绿肥在土壤肥力改良与经济效益提升方面的潜力.设柿子园清耕、种植白三叶草2个处理,于2017年9月14日分别采集0～10、10～20、20～30和30～40 cm土层样品,以分析两个处理对土壤有机质、速效氮、微生物生物量碳、氮和酶活性的影响.结果表明: 与清耕相比,生草后的整个被测土层的有机质、速效氮、微生物生物量碳、氮及脲酶、蔗糖酶、过氧化氢酶、碱性磷酸酶活性均增加,其中,0～10 cm土层生草处理的有机质、微生物生物量碳增加效果显著,10～20 cm土层速效氮含量增加效果显著,0～20 cm土层中脲酶活性显著增加,而过氧化氢酶活性、蔗糖酶及土壤酶活性的几何平均值(GME)则在整个被测土层都显著增加.表明果园生草能改善土壤肥力状况,在一定程度上可减少化肥氮投入量,提高果园经济效益,是一种优良的果园栽培模式.     

Cover crop, rye residue and in-furrow treatment effects on thrips

Abstract:  Thrips and thrips damage to cotton and peanut plants were compared in plots with in-furrow treatments of aldicarb, phorate and diammonium phosphate (DAP) fertilizer under two tillage regimes with a winter cover of crimson clover and under different levels of rye residue ground cover. Adult and larval thrips numbers were significantly lower in cotton plots following winter crimson clover cultivation compared with no-cover plots in all 3 years. Thrips numbers did not differ with respect to the in-furrow treatments in the clover plots, but in the no-cover plots, they were significantly higher in the untreated control and DAP treatments compared with the aldicarb treatment. Thrips damage was higher in the no-cover than the clover plots except in the aldicarb treatments. Within the cover crop plots, thrips damage was highest in the control and phorate treatments and similar in the DAP and aldicarb treatments. There was an inverse relationship between the amount of rye residue ground cover and thrips density and thrips damage in cotton and peanuts. There was also an inverse relationship between the density of rye residue and damage to peanuts from Bunyaviridae tospovirus. Cotton yield was reduced in the cover crop plots and was not measured in the rye residue and peanut plots. These results suggest that ground cover alone decreases thrips numbers and thrips damage in both cotton and peanuts and that a winter crimson clover cover and an in-furrow treatment of DAP enhanced plant protection from thrips in cotton.     

Susceptibility to take‐all of cereal and grass species,and their effects on pathogen inoculum

Two field trials were conducted to investigate different herbage grasses and cereals for their susceptibility to the disease take‐all, for their impact on concentrations of the pathogen, Gaeumannomyces graminis var. tritici (Ggt), in soil and for their effect on development of take‐all in a subsequent wheat crop. In the herbage grass trial, Bromus willdenowii was highly susceptible to Ggt, produced the greatest post‐senescence Ggt concentrations in soil and highest incidence of take‐all in following wheat crop. Lolium perenne, Lolium multiflorum and Festuca arundinacea supported low Ggt soil concentrations and fallow the least. The relationship between susceptibility to Ggt and post‐senescence concentrations in soil differed between pasture grasses and cereals. In a trial in which Ggt was added to half the plots and where wheat, barley, triticale, rye or fallow were compared, the susceptibility of the cereals to take‐all was not clearly linked to post‐harvest soil Ggt concentrations. In particular, triticale and rye had low and negligible take‐all infection respectively, but greater post‐harvest soil Ggt concentrations than barley or wheat. This indicates that low Ggt concentrations on roots may build up during crop senescence on some cereals. Soil Ggt concentrations were greater following harvest in inoculated plots sown to cereals, but in the second year there was more take‐all in the previously non‐inoculated than inoculated plots. Thus, the grass and cereal species differed in susceptibility to take‐all, in their impact on Ggt multiplication and in associated take‐all severity in following wheat crop.     

Organic farming affects the potential of a granivorous carabid beetle to control arable weeds at local and landscape scales

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Weed performance in crop rotations with and without leys and at different nitrogen levels

Weed populations were studied from a 26-year-old field experiment in southern Sweden with three different 6-year crop rotations, each with four rates of nitrogen application. The rotations differed in that one had a two-year legume-grass ley, another had a two-year grass ley, and that the third had spring wheat followed by a repeatedly harrowed fallow. The leys and the fallow were followed by turnip rape, winter wheat, oats and barley which was undersown in the two ley rotations. Data on weed biomass, collected in one season, were subjected to multivariate analysis.
Winter turnip rape had the highest weed biomass. However, of the several weed species, only Matricaria perforata Merat was important in wheat (the crop following turnip rape in the rotation). The weed flora did not differ consistently between rotations. We conclude that none of the three rotations had developed any major weed problems under the past weed management regime (herbicides applied to cereal crops).
There was no consistent effect of nitrogen fertilisation on total weed biomass in any of the three rotations. However, when comparing the weed floras in winter wheat, turnip rape and oats, the unfertilised plots differed from the plots receiving nitrogen. In the two latter crops, the abundant, low-growing annual Stellaria media (L.) Vil. performed best in fertilised plots with dense stands. Equisetum arvense L., the most abundant perennial weed, was important only in unfertilised plots.     

Influence of fertilization on the Colorado potato beetle, Leptinotarsa decemlineata, in organic potato production

The abundance of the Colorado potato beetle, Leptinotarsa decemlineata (Say), in organically grown potato did not change significantly in response to increasing rates of dehydrated poultry manure. However, peaks of abundance of larvae were shifted forward in time in response to the high rate of organic fertilizer. Tests using excised foliage showed that the shift was not caused by differential larval mortality or longer developmental times. Time allocation to resting, walking, and feeding by adults was similar regardless of fertilizer rate. Adult foliage consumption was unaffected by organic fertilizer rates in no choice tests and significantly affected in few choice tests. A 22% longer larval development time on plants treated with low fertilizer rate than on plants with high rate was the most significant effect. Even though maximum plant height, canopy, biomass, and yield were significantly smaller in the organic than in conventional plots, the suitability of the plants was not affected except for reduced feeding by summer beetles. Summer adults spent less time feeding and consumed two to five times less foliage on organic potato than on inorganically fertilized and conventionally produced plants. The overall influence of fertilizer on Colorado potato beetle populations was limited and therefore can only play a secondary role in management strategies for organic potato. Avoidance of excessive organic fertilizer that promotes short larval development time and extension of the period over which large Colorado potato beetle larvae are present should be recommended.     

Cereal weeds variation in middle Egypt: Role of crop family in weed composition

Cereals occupies a major part in the diet of humans globally, participating more to our daily protein and calorie intake than any other crop. The present study highlight the weed flora of cereal crops compared to other crops in middle Egypt and their distribution. Ninety-two weed species were recorded in the all studied crops, cereal and other crops; in the studied area belong to 67 genera and 20 families. Egyptian clover; showed the highest numbers of both weed species and genera followed by wheat, on contrast the lowest weed species and genera numbers were recorded associated with Solanaceous crops tomato and pepper. Wheat crops exhibited the highest number of weed species, among cereals, followed by maize crop, while the lowest weed species number was detected in barley crop. Chenopodium murale, Cynodon dactylon, Convolvulus arvensis and Malva parviflora were the most frequent species in winter cereals, while Echinochloa colona, P. oleraceae were the most frequent weeds in summer cereals. Chorological analysis of the recorded weed species showed that cosmopolitan elements showed the highest numbers in total weed flora Differences in weed species compositions were fundamentally influenced by seasonal priority. Based on TWINSPAN and Ward classifications, crop family showed slightly effect as a factor affecting weed composition.     

Landscape-scale crop diversity interacts with local management to determine ground beetle diversity

Crop diversification and maintenance of semi-natural habitats (grasslands and field boundaries) are suggested to enhance farmland biodiversity, but the relative importance of these factors remains poorly known. We evaluated how crop diversity and availability of semi-natural grasslands at a landscape-scale interacted with local farming management (three management types from low to high intensity: ley < winter wheat < sugar beet) in their effect on ground beetle assemblages in southern Sweden. Ground beetle diversity increased with crop diversity either independently of local management (Simpson species diversity), or only in the less intensively managed habitats (rarefied species richness). While ground beetle diversity in leys tended to increase with field boundary length, no such relationship was observed in winter wheat or sugar beet fields. In contrast, the landscape proportions of leys and semi-natural grasslands did not affect ground beetle species richness and diversity. We conclude that (a) semi-natural grasslands and leys may not function as source habitats at a landscape-scale if they comprise a low proportion of the total land-use, while (b) increasing crop diversity is correlated to ground beetle richness and diversity in agricultural landscapes dominated by arable land. The beneficial effect of landscape-scale crop diversification on farmland biodiversity may depend on the general level of agricultural intensity of a region.     

Effects of fertiliser addition and subsequent gopher disturbance on a serpentine annual grassland community

Summary Application of slow release fertiliser to small (0.5x1 m) plots within a serpentine annual grassland community led to significant increases in above-ground biomass and a shift in species relative abundances. In fertilised plots the native forb species which usually dominate the grassland were almost totally replaced by grasses. In the years following initial fertiliser application, a heavy mulch formed from the previous year's grass growth allowed establishment of grass species such as Bromus mollis but significantly reduced forb establishment. Gopher disturbance of fertilised plots in the second and third years of the experiment effectively removed the grass mulch and allowed re-establishment of forb species.     

Species richness in agroecosystems: the effect of landscape, habitat and farm management

It has been suggested that biodiversity in agroecosystems depends on both landscape heterogeneity and farm management, but at the same time, studies of biodiversity in relation to both landscape variables and farm management are rare. We investigated the species richness of plants, butterflies, carabids, rove beetles and the diversity of spiders in cereal fields, leys (grass and clover crop) and semi-natural pastures at 16 farms in Central East Sweden. The farms were divided into eight pairs of one conventional and one organic farm to enable us to separate the effects of landscape and farm management on biodiversity. The pairing was based on land use, location, and landscape features. Species richness of different taxonomic groups was generally not correlated. There were no differences in species richness between the farming systems, except for carabids that had higher numbers of species on conventional farms. The species richness generally increased with landscape heterogeneity on a farm scale. Habitat type had a major effect on the species richness for most groups, with most species found in pastures and leys. The correlations between species richness and landscape variables on a farm scale, and not on a scale of multiple farms, identify farmers as the important decision-maker in conservation issues for these taxonomic groups. We discuss the role of species richness of pests' natural enemies for biological control and conservation strategies of the more common species in the agricultural landscape.     

Phytoestrogens and Their Metabolites in Bulk-Tank Milk: Effects of Farm Management and Season

Phytoestrogens have structures similar to endogenous steroids and may induce or inhibit the response of hormone receptors. The objectives of the present study were to compare the effects of long-term vs. short-term grassland management in organic and conventional dairy production systems, compare organic and conventional production systems and assess seasonal variation on phytoestrogen concentrations in bulk-tank milk. The concentrations of phytoestrogens were analyzed in bulk-tank milk sampled three times in two subsequent years from 28 dairy farms: Fourteen organic (ORG) dairy farms with either short-term or long-term grassland management were paired with 14 conventional (CON) farms with respect to grassland management. Grassland management varied in terms of time since establishment. Short-term grassland management (SG) was defined as establishment or reseeding every fourth year or more often, and long-term grassland management (LG) was defined as less frequent establishment or reseeding. The proportion of red clover (Trifolium pretense L.) in the herbage was positively correlated with milk concentrations of the mammalian isoflavone equol. Therefore, organically produced bulk-tank milk contained more equol than conventionally produced milk, and milk from ORG-SG farms had more equol than milk from ORG-LG farms. Milk produced during the indoor-feeding periods had more equol than milk produced during the outdoor feeding period, because pastures contained less red clover than fields intended for silage production. Organically produced milk had also higher concentrations of the mammalian lignan enterolactone, but in contrast to equol, concentrations increased in the outdoor-feeding periods compared to the indoor-feeding periods. There were no indications of fertility problems on ORG-SG farms who had the highest red clover proportions in the herbage. This study shows that production system, grassland management, and season affect milk concentrations of phytoestrogens. However, compared to soy products, milk concentrations of phytoestrogens are low and future studies are required to investigate if the intake of phytoestrogens from dairy products has physiological effects in humans.     

The effect of cutting, mulching and applications of farmyard manure on nitrogen fixation in a red clover/grass sward

In organic farming, maximising the amount of nitrogen (N) which is fixed and retained within the soil is of paramount importance for the yield of the following crop. The aim of this study was to establish the extent to which increased soil fertility, farmyard manure (FYM) applications and/or mulching, could adversely affect fixation. At two sites, situated in the South West (SW) and North East (NE) of England, N(2) fixation was estimated in 'organically' managed red clover/grass plots, both with and without green manure (i.e. surface mulched) and/or the addition of FYM. The FYM was incorporated into the seedbeds at both sites in autumn 2002 at the rate of 170 kg total Nha(-1), as either well-composted (SW site), or not actively-composted (NE site) manures. The same FYM application rate was repeated as top-dressings to both sites in autumn 2003. The plots were cut three or four times each year over two growing seasons. In the first harvest year (2003), incorporation of FYM had beneficial effects of increasing dry matter and N yields significantly at the first cut, but there were no significant differences in subsequent cuts. The same pattern was found in the second harvest year (2004) after the top dressings of FYM, suggesting that most of the N in both types of FYM was in recalcitrant forms. Over the two growing seasons, mulching did not affect red clover/grass dry matter or N yields, but did reduce the proportion of N(2) fixed, by up to 60 kg Nha(-1) when compared with plots from which the clover/grass herbage was cut and removed. Thus, the gain in N from FYM or green manure tended to be offset by a similar reduction in N(2) fixation. These results demonstrate the close association between the availability of soil N and the feed-back system which operates on N(2) fixation by red clover.     

Effect of agricultural production systems on the potato metabolome

Potato (Solanum tuberosum L.) cv. Santé was grown over 2 years under both conventional and organic fertiliser and crop protection regimes. The tuber metabolome was analysed using mass-spectrometry (MS) based approaches, principally liquid chromatography (LC)–MS and gas chromatography (GC)–MS. Data were analysed using Principal Components Analysis (PCA) and Analysis of Variance (ANOVA) to assess any differences between production practices. GC–MS analysis of non-polar metabolites did not detect any statistically significant differences, but GC–MS analysis of polar compounds identified 83 metabolites showing significant differences in the metabolome between the fertiliser treatments. Of the 62 metabolites that were less abundant in tuber samples from organic compared with conventionally fertilised crops, consistent year on year differences were dominated by free amino acids. The effect on free amino acids is associated with the lower nitrogen (N) content of the organically grown potatoes in this instance (50 % lower than for conventional production). LC–MS provided indications that levels of certain glycoalkaloids may be lower under the organic fertiliser regime in one growing season. Differences associated with the crop protection measures used were much less consistent, and relatively small, compared with the fertiliser effects found.