Sixty years of Dutch nitrogen fertiliser experiments, an overview of the effects of soil type, fertiliser input, management and of developments in time

Data of nitrogen fertilization experiments of 1934 - 1994 have been analysed, using models for N uptake and dry matter (DM) yield. Both models were affected by fertilizer level, soil type, soil organic matter content, grassland use, cutting frequency, grassland renovation, white clover content and the N content analysis (Crude Protein or total-N). Effects on Soil Nitrogen Supply (SNS), Apparent Nitrogen Recovery (ANR) and Nitrogen Use Efficiency (NUE) are discussed. Differences in SNS, ANR and NUE between sand and clay were small, SNS on poorly drained peat soil was 60 and 80 kg N per ha higher than on clay and sand, respectively, ANR on poorly drained peat soil was 7 and 10% lower. The NUE was similar on sand, clay and poorly drained peat. ANR was low at low N application levels, due to immobilization. ANR increased from 35% to 65% at application levels of 50 and 250 kg N per ha, respectively. At application levels of more than 250 kg N per ha, ANR decreased. NUE decreased from 45 to 29 kg DM per kg N with increasing N application levels of 0 and 550 kg per ha. It is suggested that for a good N utilization a minimum N application of 100 kg N per ha should be used. SNS increased by a mixed use of grazing and cutting with 27 and 40 kg N per ha for sand/clay and poorly drained peat respectively. ANR on sand decreased from 5 to 10% at applications of 200 and 500 kg N per ha and NUE decreased with 1-2 kg DM per kg N. The effect of grazing was stronger under pure grazing than with a mixed use of grazing and cutting. Increasing the cutting frequency from 3 to 8 cuts per year had no effect on SNS, increased ANR with 0-20% and decreased NUE with 4-7 kg DM per kg N. The positive effect of the higher ANR compensated the lower NUE at application levels of 400 kg N per ha. Changes in ANR over the last sixty years can be explained by changes in experimental conditions, experimental treatments and chemical analysis. Changes in NUE can be explained by a higher proportion of perennial ryegrass and genetic improvement.

Overall animal welfare reviewed. Part 3: welfare assessment based on needs and supported by expert opinion

Welfare concerns that matter to animals is their state of need. Satisfaction and frustration of needs are associated with emotional states, the subjective experience of which directly determines the welfare status of an animal. Because emotional states are difficult to assess, overall welfare assessment (OWA) is best approached as an assessment of needs. For actual OWA, a list of needs must be formulated. Different authors have formulated different lists. From these lists a concept need-list was constructed. For validation the needs-based approach for OWA was discussed in interviews with experts (n=21) in the field of ethology and other welfare related sciences. These experts generally used mental terminology to define welfare, but when asked to classify their definition of welfare, many preferred a definition in terms of measurable parameters or a combination of both mental terms (feelings) and measurables. Most experts believed that welfare can be assessed objectively and that the problem of OWA is indeed best approached through an assessment of needs. Experts differ as to the exact composition of the list of needs. A list of needs is formulated which we intend to use for OWA in the case of sows.

Herbage and animal production responses to fertilizer nitrogen in perennial ryegrass swards. II. Rotational grazing and cutting

The yield response of grass swards to fertilizer nitrogen (N) differs under cutting and grazing, as grazing cattle exert positive and negative effects on pasture production, with varying negative effects on different soil types. Nevertheless, current N fertilization recommendations in the Netherlands are based mainly on economic cost-benefit analyses of long-term cutting trials in small plots. To contribute to formulation of improved N fertilizer recommendations for grassland, experiments were carried out on two soil types and under different management regimes. The effect of fertilizer N application on grassland production and sward quality in perennial ryegrass swards was studied during a number of consecutive years under both rotational grazing and 4-weekly cutting. Experiment 1 was performed with dairy cows on a loam soil at 250 and 550 kg fertilizer N ha-1 year-1. Experiment 2 was performed with beef cattle on a sand soil and fertilizer rates varying from 250 to 700 kg N ha-1 year-1 under grazing and from 0 to 700 kg N ha-1 year-1 under cutting. The results indicate that on loam, N had no effect on sward quality. In the second experimental year, total herbage yield under grazing was almost 10% higher than under cutting at 250 kg N ha-1 year-1 due to recycling of N, whereas at 550 kg N ha-1 year-1 the yield under grazing and cutting was the same. On sand, the economically optimum fertilizer application rate was on average 430 kg N ha-1 year-1 for 4-weekly cutting. Under grazing and at whole system level (integrated grazing and mowing for silage), the optimum rate was below 250 kg N ha-1 year-1. Under grazing on the sand soil, N aggravated sward deterioration due to treading, poaching and especially urine scorching. This was reflected in an increased absence frequency of rooted perennial ryegrass tillers in quadrats with an area of 1 dm2 at increasing fertilizer N application rates. It is concluded that current fertilizer N recommendations for grassland can be further refined by taking into account the positive and negative effects of grazing cattle, in dependence of soil type and level of N supply.

Overall animal welfare assessment reviewed. Part 1: Is it possible?

Several authors have concluded that scientists should not attempt to perform overall animal welfare assessment (OWA). They argue that scientists have continued to fail to make progress in this area and that value judgements are inherently involved in OWA for which science cannot provide answers. We take a more positive attitude toward OWA and argue that scientists should avoid creating a self-fulfilling prophecy. OWA is necessary for making actual moral and political decisions. Science has already accumulated much relevant information about welfare and this information should be applied in decision making. The task of OWA is to assess welfare based on knowledge of the biological needs of animals. Weighting of welfare relevant factors constitutes a problem. However, when scientists cannot provide empirical data to solve weighting issues, this does not mean that rational answers cannot be found, e.g. in the form of procedural rules. OWA is conceived as a problem of multi-criteria decision making with fuzzy information. If focuses on the descriptive aspect of welfare, i.e. on what the welfare status of the animals really is without taking an ethical stance. The welfare status of animals depends on their biology and on the way animals assess their own welfare. It does not depend on how it happens to be perceived by us. Even though OWA necessarily remains a human activity, it is not arbitrary, nor does it allow of multiple 'correct' answers. OWA is a descriptive activity that can achieve more and more accuracy as science proceeds.

Mixing specialized farming systems in Flevoland (The Netherlands): agronomic, environmental and socio-economic effects

Mixed farming systems have potential agronomic, environmental and socio-economic advantages over specialized farming systems. This paper attempts to quantify these advantages for the Dutch province Flevoland. A mixed farming system at regional level is characterized by intensive cooperation between two or more specialized farms, each producing crop or animal products. To test the hypothesis that such a mixed farming system might improve sustainability of agriculture in Flevoland, nutrient balances, labour requirements and labour income were quantified for a specialized arable farm, a specialized dairy farm and both combined into a mixed farming system, exchanging land, labour and machinery. Scope for reduced biocide use in the mixed farming system was assessed in a qualitative way. In the mixed farming system, labour income per ha was 25% higher. Seventy percent of this increase could be explained through higher yields per ha of the profitable crops ware potato (Solanum tuberosum) and sugar beet (Beta vulgaris). The remaining 30% resulted from lower costs, mainly through a better utilization of available labour. Differences between the combined nutrient balance of both specialized farms and that of the mixed farming system were small. Indications of reduced biocide use in the mixed farming system could not be found. It was concluded that in a mixed farming system, it is possible to realize a higher income without increasing environmental pollution. Key factor is the ratio between animal and arable production, determining the extent to which crop rotations can be widened and the relative amounts of slurry that can be applied to grassland.

Limits to intensity of milk production in sandy areas in The Netherlands

Agricultural land in sandy areas is mainly in use by dairy farms. As a result of intensive fertilisation and irrigation, environmental quality is threatened by lost nutrients and lowered groundwater levels. Therefore, Dutch government put decreasing limits to losses of nutrients, with lowest values for well-drained sandy soils. Besides, use of groundwater for irrigation will be restricted. Reducing milk production per hectare can be effective to reduce nutrient losses but is costly, as is the increase of output of nutrients by exporting manure. Improved resource management, leading to reduced inputs per kg milk, might be a more attractive option to realise both environmental and economic goals. This paper describes a procedure to quantify the impact of management on the limits of milk production per hectare on well-drained sandy soils, at defined maximum levels of permitted nutrient losses. The procedure has been applied to a range of farming systems, in order of increasing complexity of nutrient management. It is concluded that current average milk production intensity (12,400 kg ha(-1) yr(-1)) has to be reduced drastically if farm management is not successful in increasing the conversion of dietary N (into milk and body weight) and the re-use of N in manure. On the other hand, results suggest that an intensity of almost 15,000 kg ha(-1) yr(-1) should be attainable by best farmers.

The effect of the rate and method of nitrogen application on nitrogen uptake and utilization by broccoli (Brassica oleracea var. italica)

The effect of the rate and method of nitrogen application on nitrogen uptake and utilization by broccoli (Brassica oleracea var. italica) was studied in four field experiments. The methods of application were broadcast application vs band placement and split application. Maximum uptake of nitrogen by the crop was around 300 kg ha-1. In one experiment, band placement positively influenced nitrogen uptake. Split application did not influence nitrogen uptake. Nitrogen application resulted in a higher head dry matter production, but the efficiency of nitrogen utilization for the production of head dry matter decreased with higher amounts of nitrogen applied. Nitrogen application decreased the dry matter content of the heads. In half of the experiments, band placement of nitrogen fertilizer resulted in extra head dry matter production and lower head dry matter contents. At the optimum rates of band placed nitrogen application, the nitrogen harvest index in the experiments ranged from 27 to 30%. The amount of mineral nitrogen in the soil at harvest generally increased with increasing amounts of nitrogen applied. Band placement resulted only in one experiment in lower amounts of mineral nitrogen in the soil at harvest. The mineral nitrogen in the soil at harvest can be unevenly horizontally distributed, both with broadcast application and band placement of nitrogen fertilizer. The amount of nitrogen unaccounted for at harvest increased with increasing amounts of nitrogen applied, but was always less than the amount of nitrogen in crop residues. At the optimum rates of band placed nitrogen application, the amount of nitrogen in crop residues ranged from 120 to 155 kg ha-1. With broccoli cultivation, the nitrogen in the crop residues forms the single largest source of potential loss of nitrogen to the environment.

Overall animal welfare reviewed. Part 2: Assessment tables and schemes

In the scientific literature several attempts have been made to systematically assess the overall welfare-status of animals in relation to housing and management. This paper reviews assessment tables and schemes that have been constructed to this end. These tables and schemes have a tabular format that allows an assessment of housing systems using a list of welfare-relevant attributes (properties of the housing system). Rather than identifying deficits, the focus of this review is on finding positive recommendations for the purpose of developing a method for overall welfare assessment (OWA) on a scientific basis. The main recommendation is to use the tabular format as representation formalism for OWA. The concept of linked tables provides the key to performing OWA on a scientific basis in an explicit and systematic way.

Efficient resource management in dairy farming on sandy soil

Sandy soils in the Netherlands are mainly used for dairy farming. As a result of intensification of dairy farming in the recent past, valued functions of sandy regions now are threatened by high emissions of nitrogen (N) and phosphorus (P) and by increased water consumption by forage crops. Improved utilization efficiency of resources is proposed as a strategy to realise environmental targets in an economically viable way. Experimental results of the prototype system 'De Marke' indicate that an average intensive commercial farm can halve inputs of fertilizers and feeds at least, without the need to reduce milk yield/ha or to export slurry. Water consumption can be reduced by 13%, increasing groundwater 'production' by 570 msuperscript 3/ha. Nitrate concentration in the upper groundwater decreased from 200 to 50 mg/litre. Changes in soil fertility did not lead to serious agricultural problems but costs of milk production increased by 5%. However, additional costs may be compensated for if the extra groundwater is 'harvested' by water companies, because of high cost of purification of surface water and consumer preference for drinking groundwater instead of river-water. In 1999, the examined strategy of improved resource management was implemented on 12 commercial farms, representing the full range of conditions for dairy farming in the Netherlands.

Design of farming systems for low input conditions: principles and implications based on scenario studies with feed allocation in livestock production

This study addresses the issue of designing farming systems for low input conditions. By focusing on the problem of feed (resource) allocation in livestock systems it provides clues for the design of alternative agricultural systems and systems in general. Linear programming (LP) is used to examine system behaviour under conditions of varying feed resource qualities, for individual animal production levels that range from 0.75 to 3.00 times maintenance. Milk yield, animal numbers and amounts of feed offered or refused are measures of system performance in two hypothetical cases representative for actual farming systems. Case 1 considers available feed as one aggregated resource, with an average nutritive value ranging from that of straw to that of high quality forage. It establishes the individual animal output level that is required to achieve maximum total system output from a given feed resource. In Case 2, animals of different production levels are allowed to select between two feed resources that, through proper definition of the their proportions on offer, on average represent the same feed quality scale as in Case 1. The possibility of selection, however, allows the nutritive value of the actual intake to differ from the average nutritive value of feed offered. Better feed and higher (potential) individual animal output tend to increase total system output in terms of milk, by reducing the number of animals. Nevertheless, the term 'damning objective' is introduced to express that high targets for subsystem output reduces total system output if subsystem requirements exceed resource availability. Moreover, heterogeneity of (feed) resources can increase system output by using more production units with lower individual output. The results are tested against farmers' practice and situations reported in literature. Implications for the design of sustainable systems and further research are discussed.