On-farm Measurements Research Articles

Manure nutrient application on a Chinese dairy farm with arable land: A case study based on Dutch experience of equilibrium fertilization

For a Chinese dairy farm with 2200 milking cows, the annual manure production and manure nutrients (nitrogen and phosphorus) were estimated. Gaseous nitrogen losses from cattle housing with scraped solid floors were based on on-farm measurements. Based on experiences from the Netherlands, nutrient levels in the solid and liquid fractions after slurry separation were estimated. On the basis of assumptions for nutrient losses during covered lagoon storage and land application of the liquid fraction, nitrogen and phosphorous fertilization rates were calculated for the 67 hm2 of agricultural land that receive the liquid fraction by gravity irrigation. The results show that the application rates of nitrogen and phosphorous significantly exceed the crop needs, which will probably result in losses to soil and water. In order to aim for a balance between nutrient application and crop needs and, as such, reduce environmental harm, the authors recommend to establish application standards for nitrogen and phosphorous on arable land in China and to formulate farm-specific Nutrient Management Plans. Keywords: dairy manure, nutrient balance, dairy farm, over-fertilization, nutrient application standard, environmental protection DOI: 10.25165/j.ijabe.20171004.3082 Citation: Melse R W, de Buisonje F E, Qiao W, Dong R J. Manure nutrient application on a Chinese dairy farm with arable land: A case study based on Dutch experience of equilibrium fertilization. Int J Agric & Biol Eng, 2017; 10(4): 182–188.

Effect of Calf Birth Weight on Milk Production of Holstein Dairy Cattle in Desert Climate

The hypothesis in this study was that calf birth weight (CBW) would effect on cow's milk production. Data were collected from two commercial dairy milking 15,000 Holsteins in central region of Iran from 2006 to 2012. Animals were enrolled at parturition until 7,737 calvings were available for analysis. Data consisted of on-farm measurements of calf birth weight and milk production, and data were analyzed using a multivariable regression model. Independent variables were parity, herd-year-season, calving interval, calving age, retained placenta, days open, dry period length, days in milk, linear and quadratic CBW. The mean CBW was 40.84 ± 4.9 kg (SD) with a range of 20 to 60 kg. There was a trend for milk305 based on calf birth weight, i.e., the amount of milk305 of dam was significantly dependent on that weight of calf was born (P < 0.01). Cows with CBW between 20 and 25 kg had the lowest of milk production. By increasing of CBW range up to 40 and 45 kg, the trend of milk production increased and then decreasing trend observed. In conclusion, calf birth weight could be considered as an important trait in dairy cattle breeding programs.

Simplifying the Welfare Quality® assessment protocol for broiler chicken welfare

Welfare Quality® (WQ) assessment protocols place the emphasis on animal-based measures as an indicator for animal welfare. Stakeholders, however, emphasize that a reduction in the time taken to complete the protocol is essential to improve practical applicability. We studied the potential for reduction in time to complete the WQ broiler assessment protocol and present some modifications to the protocol correcting a few errors in the original calculations. Data was used from 180 flocks assessed on-farm and 150 flocks assessed at the slaughter plant. Correlations between variables were calculated, and where correlation was moderate, meaningful and promising (in terms of time reduction), simplification was considered using one variable predicted from another variable. Correlation analysis revealed a promising correlation between severe hock burn and gait scores on-farm. Therefore, prediction of gait scores using hock burn scores was studied further as a possible simplification strategy (strategy 1). Measurements of footpad dermatitis, hock burn, cleanliness and gait score on-farm correlated moderately to highly with slaughter plant measurements of footpad dermatitis and/or hock burn, supporting substitution of on-farm measurements with slaughter plant data. A simplification analysis was performed using footpad dermatitis, hock burn, cleanliness and gait scores measured on-farm predicted from slaughter plant measurements of footpad dermatitis and hock burn (strategy 2). Simplification strategies were compared with the full assessment protocol. Close agreement was found between the full protocol and both simplification strategies although large confidence intervals were found for specificity of the simplified models. It is concluded that the proposed simplification strategies are encouraging; strategy 1 can reduce the time to complete the on-farm assessment by ~1 h (25% to 33% reduction) and strategy 2 can reduce on-farm assessment time by ~2 h (50% to 67% reduction). Both simplification strategies should, however, be validated further, and tested on farms with a wide distribution across the different welfare categories of WQ.

Improving Corn Production in Southeast Kansas

Corn performance and yield varies as a function of the growing environment and soil properties. Components contributing to yield in corn were examined through on-farm measurements of soil properties in southeast Kansas. Environmental variability between the 2013, 2014, and 2015 growing seasons contributed to changes in yield. Management can also impact the amount of harvested yield.

Identification of Yield-Limiting Factors in Southeast Kansas Cropping Systems

Crop performance and yield within production fields varies as a function of growing environment and soil properties within the field. Components contributing to yield in corn, wheat, and soybean production were examined through on-farm measurements of soil properties in southeast Kansas. Additional tests in research plots explored components contributing to yield in greater detail. Environmental variability between the 2013 and 2014 growing seasons contributed to differences in yield. Additional variability in soil parameters influenced crop performance, particularly for soils high in clay content.

Measuring methane emissions from two dairy farms: Seasonal and manure-management effects

There is a need to improve the understanding of methane (CH4) emissions on multiple spatial and temporal scales, and on a sector basis. Livestock are significant contributors to the CH4 budget, with emissions coming from enteric fermentation by ruminants and management of liquid manure. Inventory estimates for methane emissions are based on methodology that needs to be verified with actual on-farm measurements. Responding to these needs, the objectives of this study were to apply the backward Lagrangian Stochastic (bLS) technique on small dairy farms (50-100 lactating cows) and to examine its suitability to determine CH4 emissions from whole farms and partition emissions from cattle and manure. Measurement campaigns were selected to characterize the emission response to farm management activities and seasonal changes. At both farms the whole-farm emission rate was measured when the liquid manure storages were either full or emptied. Emissions from manure were substantial, and in the fall when the manure storage was full, 60% of the whole farm emissions came from the manure storage. Substantial seasonal differences in whole-farm emissions were observed, with fall season emissions being ∼40% higher than in the spring due to much higher manure emissions in the fall (673glactating-cow−1d−1) than the spring (249glactating-cow−1d−1). Peak emissions from stored manure were 47kgCH4h−1, (730glactating-cow−1h−1) during agitation. The enteric emission rate from the animals (after subtracting estimated barn floor emissions) showed clear diurnal variation and on a daily basis was similar for both seasons, ranging between 270 and 380glactating cow−1d−1. Implied Ym values were lower than the IPCC default value. Methane emissions from manure exhibited pronounced temporal variation on multiple time-frames and as a result, more research is needed to fully describe annual CH4 emissions from liquid manure management.

Ventilation rate measurements at a mechanically-ventilated pig finishing quad barn

With concentrated animal feeding operations (CAFOs) becoming larger and more intensive, air pollutant emissions from these facilities are of increasing concern for regulators and the public, and on-farm measurements of emissions are needed. A critical step in determining air pollutant emissions from the barns at these facilities is the accurate assessment and continuous monitoring of the barn ventilation rates. One of the most recent efforts to accurately determine barn ventilation rate was to continuously monitor fan operation, differential static pressure, fan speed, and air density related environmental variables, coupled with in-situ fan performance assessments at a range of static pressures, as applied in the 24-month National Air Emissions Monitoring Study (NAEMS). Uncertainty analyses associated with these calculations aided in characterising and qualifying the measurements. This paper describes methods used in the NAEMS to determine ventilation rates of four rooms (rooms 5–8) in a mechanically-ventilated pig finishing quad barn. The overall 2-yr average daily dry-standard ventilation rates (mean ± SD) were 13.5 ± 11.3, 13.8 ± 11.6, 14.5 ± 12.9, and 13.6 ± 12.9 m3 [dry-standard] s−1 for rooms 5–8, respectively. Thorough uncertainty analyses demonstrated that the estimated uncertainty of the ventilation rate (dry-standard) under typical site conditions decreased from 9.4% to 4.1% between the minimum (3.7 m3 [ds] s−1) and maximum (45.2 m3 [ds] s−1) capacities of the ventilation system. These results confirmed that larger numbers of operating fans lead to lower relative uncertainties for barn ventilation rates and that the uncertainty of ventilation rate measurements can be reduced by improved and more frequent in-situ fan calibrations.

Mitigation potential of soil conservation in maize cropping on steep slopes

Maize (Zea mays) cropping has greatly increased in Southeast Asia since the mid-1990s, mainly by expanding its production into steep forested uplands. This led to severe erosion, soil degradation, and strong environmental impacts. This study aimed at assessing the magnitude of erosion in maize and the mitigation potentiality of soil conservation measures in such environments. Bounded experimental plots established in two catchments of the Son La province of Northwest Vietnam were monitored during 2009–2011. Three soil conservation measures represented by Guinea grass (Panicum maximum) barriers, minimum tillage with Pinto peanut (Arachis pintoi) as a cover crop, and minimum tillage with relay cropping of Adzuki beans (Phaseolus calcaratus) were compared against the current farmers’ maize cropping practice based on slashing, burning, and ploughing. Additional on-farm measurements of soil loss on maize fields were made using sediment fences on six convergent unbounded fields in 2010 and 2011. Under farmers’ practice, annual soil losses of experimental plots reached up to 174tha−1, being higher than those from sediment-fence plots (up to 111tha−1). The pattern of erosion events, however, was similar in both methods. Most of the soil loss occurred in the first weeks after sowing or under maize mono cropping when high rainfall intensities coincided with a low percent ground cover of fields. Under the prevailing conditions (1270mm rainfall, inclination 53–59%), a very high ground cover is required to keep erosion rates low, which is hardly achievable by maize mono-cropping. Conservation measures had no effect on soil loss in the year of trial establishment as rainfall was low and erosive rains fell only when ground cover by plants was already high. From the second year after establishment of soil conservation measures, erosion was reduced by 39–84% in grass barriers or by 93–100% in simultaneous cover crop treatments. Maize yields, however, decreased by 26% in grass barriers or up to 35% in cover crop plots if Pinto peanuts were not cut on time. Both of these options provided animal feed, up to 5.5tha−1yr−1 dry grass or 1.8tha−1yr−1 dry biomass of Pinto peanuts. Guinea grass even yielded higher in 2010, a dry year with erratic rainfall distribution. Minimum tillage with relay cropping reduced soil loss by 94%, while providing similar maize yields as the controls. This latter practice is a win-win situation and, hence, attractive to farmers fostering its acceptance.

Short communication: Comparison of ambient temperature, relative humidity, and temperature-humidity index between on-farm measurements and official meteorological data

The objectives of the study were to compare the climate conditions of 7 dairy farms with the climate recorded at the closest official meteorological station. Specifically, we set out to compare the ambient temperature, relative humidity, and the resulting temperature-humidity index (THI) from 7 different barns with those data obtained from the closest official meteorological stations and to compare the climate conditions between 4 different locations within 1 barn. Measures of correlation and agreement demonstrated that climate conditions differ significantly between the barn and the corresponding official meteorological stations as well as between 4 different locations inside 1 barn. The ambient temperature was higher (6.4±3.6°C) in the barn than at the official meteorological station. The relative humidity was higher at the official meteorological station (0.2±7.2%) than in the barn. The THI was higher (11.1±6.5) in the barn than at the official meteorological station. Days with an average THI≥72 were 64 and 4 out of 756 experimental d in the barn and at the official meteorological station, respectively. Also, in a comparison of 7 different barns, ambient temperature and THI were significantly higher than at the closest corresponding official meteorological station. These results indicate that climate conditions should be obtained from on-farm measurements to evaluate potential heat stress and to develop effective measures to abate heat stress of dairy cows.

A comparison of emission calculations using different modeled indicators with 1-year online measurements

The overall measurement of farm level greenhouse gas (GHG) emissions in dairy production is not feasible, from either an engineering or administrative point of view. Instead, computational model systems are used to generate emission inventories, demanding a validation by measurement data. This paper tests the GHG calculation of the dairy farm-level optimization model DAIRYDYN, including methane (CH₄) from enteric fermentation and managed manure. The model involves four emission calculation procedures (indicators), differing in the aggregation level of relevant input variables. The corresponding emission factors used by the indicators range from default per cow (activity level) emissions up to emission factors based on feed intake, manure amount, and milk production intensity. For validation of the CH₄ accounting of the model, 1-year CH₄ measurements of an experimental free-stall dairy farm in Germany are compared to model simulation results. An advantage of this interdisciplinary study is given by the correspondence of the model parameterization and simulation horizon with the experimental farm's characteristics and measurement period. The results clarify that modeled emission inventories (2,898, 4,637, 4,247, and 3,600 kg CO₂-eq. cow(-1) year(-1)) lead to more or less good approximations of online measurements (average 3,845 kg CO₂-eq. cow(-1) year(-1) (±275 owing to manure management)) depending on the indicator utilized. The more farm-specific characteristics are used by the GHG indicator; the lower is the bias of the modeled emissions. Results underline that an accurate emission calculation procedure should capture differences in energy intake, owing to milk production intensity as well as manure storage time. Despite the differences between indicator estimates, the deviation of modeled GHGs using detailed indicators in DAIRYDYN from on-farm measurements is relatively low (between -6.4% and 10.5%), compared with findings from the literature.

Associations of housing, management, milking activity, and standing and lying behavior of dairy cows milked in automatic systems

The objective of this cross-sectional study was to describe the housing, feeding management, and characteristics (parity and stage of lactation) of cows on commercial automatic milking system (AMS) dairies and their associations with the standing and lying behavior patterns and milking activity (frequency and yield) of lactating dairy cows. Thirteen AMS herds were enrolled in the study, with an average herd size of 71±30 (mean ± SD; range: 34 to 131) lactating cows. All of the herds used freestall barns, each set up for free cow traffic to the AMS. On-farm measurements were taken to determine stocking density at the freestalls (0.9±0.1 cows/stall; mean ± SD), feed bunk (0.66±0.17m of feed bunk space/cow; mean ± SD), and AMS units (55±11 cows/AMS; mean ± SD). A random sample of 30 cows/herd was selected to monitor standing and lying behavior for 4d using electronic data loggers. Times of feed delivery and feed push-up were recorded daily by the herd managers. Milking times, frequency, and yield were automatically recorded by the AMS units. Data were analyzed in a multivariable mixed regression model to determine which herd-level (housing and feeding management) and cow-level (parity, DIM, and milk yield) factors were associated with behavior and milking activity measures. Lying bout lengths were found to be negatively associated with milk yield and tended to be positively associated with more space at the feed bunk. Increased lying duration was associated with cows of lower milk production, increased space at the feed bunk, and increased frequency of feed push-up. Longer postmilking standing durations were associated with cows of higher parity. An association existed between cows milking less frequently when they were further in lactation, were of higher parity, and as stocking density at the AMS (cows/AMS) increased. Milk yield was positively associated with increased space at the feed bunk and higher parity and negatively associated with DIM. From this study, it can be concluded that increased milking frequency may be achieved in AMS herds by reducing stocking density at the AMS unit. Further, in AMS systems, greater milk yield and lying duration may be achieved by ensuring that cows have ample feed bunk space and have their feed readily available to them in the bunk.

Narrowing the agronomic yield gap with improved nitrogen use efficiency: a modeling approach

Improving nitrogen use efficiency (NUE) in the major cereals is critical for more sustainable nitrogen use in high-input agriculture, but our understanding of the potential for NUE improvement is limited by a paucity of reliable on-farm measurements. Limited on-farm data suggest that agronomic NUE (AE(N)) is lower and more variable than data from trials conducted at research stations, on which much of our understanding of AE(N) has been built. The purpose of this study was to determine the magnitude and causes of variability in AE(N) across an agricultural region, which we refer to as the achievement distribution of AE(N). The distribution of simulated AE(N) in 80 farmers' fields in an irrigated wheat system in the Yaqui Valley, Mexico, was compared with trials at a local research center (International Wheat and Maize Improvement Center; CIMMYT). An agroecosystem simulation model WNMM was used to understand factors controlling yield, AE(N), gaseous N emissions, and nitrate leaching in the region. Simulated AE(N) in the Yaqui Valley was highly variable, and mean on-farm AE(N) was 44% lower than trials with similar fertilization rates at CIMMYT. Variability in residual N supply was the most important factor determining simulated AE(N). Better split applications of N fertilizer led to almost a doubling of AE(N), increased profit, and reduced N pollution, and even larger improvements were possible with technologies that allow for direct measurement of soil N supply and plant N demand, such as site-specific nitrogen management.

Calf birth weight and its association with calf and cow survivability, disease incidence, reproductive performance, and milk production

The hypothesis was that calf birth weight (CBW) and a cow calf index [CCI; (calf weight/cow height at parturition)×100] would be associated with calf and cow survivability, disease incidence, reproductive performance, and milk production. Data were collected in a prospective cohort study from one commercial dairy milking 2,800 Holsteins in upstate NY from March 2007 to August 2007. Animals were enrolled at parturition until 1,245 calvings were available for analysis. Data consisted of on-farm measurements of morbidity, mortality, and performance, and data were analyzed using a series of multivariable models including ANOVA and time-to-event analysis. A higher CBW and a higher CCI were associated with greater odds of lameness. Compared with the lowest quartile of CBW, the odds of the dam becoming subsequently lame increased as the CBW quartiles increased from 2 to 4; odds ratio = 1.5, 2.7, 3.6, respectively. Compared with the lowest quartile of CCI, the odds of the dam becoming subsequently lame increased as the CCI quartiles increased from 2 to 4; odds ratio = 4.6, 4.7, 4.8, respectively. Assistance during parturition was associated with higher CBW and with higher CCI. Calves born from assisted parturition had significantly higher CBW (CBW = 43.7kg) and CCI (CCI = 31.4) compared with calves born from nonassisted parturition (CBW = 41.5kg and CCI = 29.7). Neither CBW nor the CCI were associated with stillbirth incidence, calf mortality past 12h of life, cow reproduction, or cow survival. We concluded that CBW, and especially the ratio of CBW to dam size, can be associated with some downstream effects, e.g., obstetrical assistance, lameness events, and milk production.

On-farm labour allocation and irrigation water use: case studies among smallholder systems in arid regions

On-farm measurements and observations of water flow, water costs and irrigation labour inputs at the individual parcel level were made in case studies of smallholder irrigation systems in sub-Saharan Africa and south-eastern Arabia. The systems, in which the water source supplied either single or multiple users, were analysed to address the fundamental issues of labour allocation for on-farm water management as this has important consequences for the success of such systems. Results show that the costs associated with accessing water influenced labour input, because when they were low the farmers tended to increase the irrigation rate and reduce the amount of time they spent distributing the water within their parcels. Conversely when water costs were high, lower flow rates and more time spent in water distribution were observed, and this resulted in more uniform irrigation and higher irrigation efficiency. Also, opportunities and demands for farmers to use their labour for activities other than irrigation can lead them to modify operational or physical aspects of the system so that they can reduce the time they spend distributing water within the parcels, particularly when the water is relatively cheap. Awareness and better understanding of how farmers may allocate their labour for water management will lead to more effective planning, design and management of smallholder irrigation systems.

Exploring diversity of crop and soil management within smallholder African farms: A dynamic model for simulation of N balances and use efficiencies at field scale

Adding a dynamic, temporal dimension to the calculation of nitrogen balances is proposed as an alternative approach to assessing the impact of crop and soil management decisions on the establishment of farmer-induced soil fertility gradients within smallholder African farms. A simulation model that operates at field scale (DYNBAL-N: DYnamic simulation of Nutrient BALances) was used to understand the mechanisms leading to differences in resource use efficiency within a farm. We focused on N balances and use efficiencies, as the advantages of increasing the complexity of the calculations by considering the dynamics of the system (relative to the widely-used static approach) are expected to be large for a highly mobile nutrient such as N. The model was tested against a wide range of maize yield data (0.2–3.4 t ha −1) from on-farm measurements undertaken in western Kenya (Vihiga, Kakamega and Teso districts), producing reasonably accurate predictions ( r 2 = 0.72). Simulation scenarios were selected by considering multiple sources of variability affecting the N balances for typical households in Shinyalu, western Kenya, using field data collected by means of interviews, participatory resource flow mapping, soil sampling and laboratory analysis. The simulation results indicated that the use efficiencies of the biophysical resources radiation, water and N varied across the different fields of the farms, strongly affected by management decisions and soil fertility status. N balances varied between −38.0 and 21.9 kg N ha −1 for the different crop and soil management scenarios. The main N flows explaining the magnitude and the sign of the N balances were N removal by harvest, and N losses by leaching (2.3–18.3 kg ha −1) and by soil erosion (0.6–14.9 kg ha −1). Different options for soil fertility management (N fertilisation rates, manure applications) were then explored for different field types within a farm using the model. The use efficiency of the N applied as mineral fertiliser varied between 15.2 and 48.4 kg grain kg −1 applied N for different crop and soil management scenarios. The results illustrated the advantages of including the temporal dimensions and considering the spatial variability in the calculation of nutrient balances, when realistic scenarios are analysed. These results also indicated that nutrient balances at field scale are of limited value as indicators of resource use efficiency, and that nutrient stocks and corresponding crop yields need to be taken into account.

Environmental risk analysis of farming systems in a semi-arid environment: effect of rotations and management practices on deep drainage

We investigated the impact of crop rotations and management practices on the water balance of farming systems in a semi-arid region of south-eastern Australia, where drainage beyond the root zone and rising water tables contribute to salinisation of soils and water streams. The CropSyst model was locally tested and used with long-term weather data to analyse the risk of deep drainage associated with alternative farming practices; water balances were estimated using both cascade and finite difference approaches. Model estimates were compared with (a) yield, biomass, phenology, soil water content and water use measured in a 5-year experiment involving two rotations, i.e. FWP (fallow-wheat–pea) and MWP (mustard–wheat–pea) and (b) yield measured in grower-managed wheat crops encompassing three seasons and broad ranges of weather, rotations, management practices and soils. In the rotation experiment, the simulations of yield were close to measured yield for wheat (observed range from ≈0 to 2.4 t ha −1; R 2 = 0.78; RMSE = 0.42 t ha −1), mustard (range from ≈0 to 0.6 t ha −1; R 2 = 0.57; RMSE = 0.20 t ha −1) and field pea (range from ≈0 to 1.4 t ha −1; R 2 = 0.72; RMSE = 0.29 t ha −1). Simulated wheat yield also compared well with on-farm measurements (observed range from ≈0 to 3.5 t ha −1; R 2 = 0.72, RMSE = 0.21 t ha −1). The model provided reasonable estimates of crop biomass, phenological development, soil water content and water use. Water use tended to be overestimated in some cases using the finite difference approach, but soil water content was well simulated in the presence of crop residues. The use of a finite-difference approach highlights the need to account for upward movement of water in the soil and its consequences on deep drainage. Median annual drainage simulated at 1.5 m was +9.1 mm for the fallow-wheat rotation, −5.4 mm for fallow-wheat–pea, −8.4 mm for mustard–wheat–pea, and +0.6 mm for wheat–wheat. The 3-year rotations (FWP and MWP) had the lowest median drainage and lowest probability of large drainage events in wet years. In the fallow-wheat rotation, median annual drainage was 24.8 mm with stubble retention and zero tillage, compared to −2.8 mm for stubble burnt and conventional tillage. Whilst the median response is indicative of comparative system performance, large episodic drainage events can be expected to be more frequent under fallow-wheat and even larger events with stubble retention and zero tillage. Stubble retention and zero tillage might be justified to increase and stabilise crop yield and reduce soil erosion but they do need to be assessed against the requirement to reduce deep drainage that is implicated in rising river and soil salinisation.

Nutrient-Balance Modeling as a Tool for Environmental Management in Aquaculture: The Case of Trout Farming in France

The control and prevention of nutrient pollution from fish farming plays an essential role in the French regulatory framework. Assessing nutrient emissions from fish farms is important in terms of farm authorization, taxation, and monitoring. Currently employed strategies involve both water sampling and empirical modeling. This article reports the work and outcomes of an expert panel that evaluated existing methodologies and their possible alternatives. The development and evaluation of a nutrient-balance approach was assessed as a potential alternative to currently used methodologies. A previously described nutrient-balance model was suggested and parameterized using expert choice, and its validity and applicability were assessed. The results stress that the nutrient-balance model provides more robust and relatively conservative waste estimates compared to the currently used methodologies. Sensitivity of the approach to the uneven data quality available at farm level, difficulties of on-farm measurements, as well as model requirements and limitations are discussed.

Nitrogen excretion in dairy cow, beef and veal cattle, pig, and rabbit farms in Northern Italy

Reference values for N excretion of different livestock production systems are required for the application of the Nitrate Directive (91/676/EC). A survey aimed to estimate N excretion from on-farm measurements of feed consumption and performance of dairy cows (104 herds, 9,984 cows), growing cattle (40 farms, 40,157 young bulls), veal calves (34 farms, 49,206 calves), growing pigs (39 farms, 161,278 pigs) and rabbits (54 farms, 65,664 reproducing does) was conducted in Veneto from 2002 to 2003. N excretion was computed as the difference between N consumption and N retained in animal products. Dairy cow yielded 8,366 ± 1,646 kg/year of milk, consumed 6,600 ± 928 kg/year of DM, containing 2.45 ± 0.2 % DM of N, and excreted 116 ± 25 kg of N/year. No significant correlation was found between milk yield and N excretion, but the correlation between dietary N concentration and N excretion was significant (r=0.66). For growing cattle, the following mean values were achieved: daily gain 1.25 ± 0.19 kg/d; feed conversion ratio 6.9 ± 0.9 kg of DM/kg, rounds/year 1.66 ± 0.38. Nitrogen consumed, retained and excreted were, respectively, 68.7 ± 5.4, 11.4 ± 1.9 and 57.3 ± 4.9 kg/place/year. For veal calves, N consumed was 24.1 ± 1.9 kg/place/year, 12.1 ± 0.8 kg of which were retained in the body and 12.0 ± 1.5 kg were excreted. For heavy pig production, N consumed, per place and per year, averaged 19.0 ± 1.9 kg, N retained was 5.2 ± 0.5 kg and N excreted was 13.8 ± 0.4 kg. In the close-cycle rabbit farms, the doe and the relative growing rabbits (43 sold per year) consumed 11.2 ± 2.2 kg, retained 3.8 ± 0.7 kg and excreted 7.4 ± 1.5 kg N/doe/year. Nitrogen excretion estimated in this work can be considered as representative of some of the main animal production systems of the North-East of Italy. These values should not be considered as fixed, otherwise the implementation of the various strategies to reduce N excretion would not be possible. They should be considered as guidelines in the assistance both to public institutions and private enterprises in the evaluation of N excretion at farm level, favouring a more accurate quantification of the excretions, an increase of N retention efficiency and a better knowledge of the requirements of agricultural land. Moreover, a major extension of the agricultural land to be fertilised with manure should be promoted.

On-farm measurements of nitrogen fixation by winter and summer legumes in the Hill and Terai regions of Nepal

Results are reported from on-farm surveys of N 2 fixation in Nepal, conducted between 1994 and 1999, involving the summer legumes soybean, mashbean and groundnut, and the winter legumes lentil and chickpea, at various locations in the Hill and Terai regions of Nepal. Additional less-detailed data were also collected for pigeonpea, grasspea and fababean. There were a total of 107 crops in the major and minor surveys. Estimates of the proportion of legume nitrogen (N) derived from N 2 fixation ( Pfix) were determined using the natural 15N abundance method. Mean estimates of Pfix for the various species were 62% (soybean), 47% (mashbean), 57% (groundnut), 78% (lentil), 79% (chickpea), 75% (pigeonpea), 87% (grasspea) and 85% (fababean). Estimates of total N fixed (including roots) were 59 kg N ha −1 (soybean), 28 kg N ha −1 (mashbean), 153 kg N ha −1 (groundnut), 72 kg N ha −1 (lentil), 84 kg N ha −1 (chickpea), 412 N ha −1 (pigeonpea) and 80 N ha −1 (grasspea and fababean). The on-farm measurements of N 2 fixation were generally similar to those of experimental crops in the same areas of the country. Correlation matrices of soil fertility parameters, shoot dry matter and N, and N 2 fixation revealed that the total amounts of N fixed were influenced primarily by crop growth. Based on the above figures, it was estimated that approximately 30,000 t N were fixed annually in Nepal by legumes, valued at US$ 15 million.

Seasonal rainfall partitioning under runon and runoff conditions on sandy soil in Niger. On-farm measurements and water balance modelling

In sparsely cropped farming systems in semi-arid tropics, rainfall partitioning can be complex due to various interactions between vertical and horizontal water flows, both in the atmosphere and in the soil. Despite this, quantifying the seasonal rainfall partitioning is essential, in order to identify options for increased yields. Results are presented on water flow components, based on field measurements and water balance modelling, for three years (1994–96) in a farmer's field cultivated with pearl millet [ Pennisetum glaucum (L.) Br.] in the Sahel (Niger). Water balance modelling was carried out for three common infiltration categories: runoff producing surfaces, surfaces receiving inflow of runon water from upstream zones, and a reference surface with zero runoff and runon. Runoff was calculated to 25%–30% of annual rainfall (which ranged from 488 to 596 mm), from crust observations, rainfall, soil wetness data, and infiltration estimates. Inflow of runon was estimated from field observations to 8%–18% of annual rainfall. The parameters in the functions for soil surface and canopy resistances were calibrated with field measurements of soil evaporation, stomatal conductance and leaf area. The model estimates of soil water contents, which were validated against neutron probe measurements, showed a reasonable agreement with observed data, with a root mean square error (RMSE) of approximately 0.02 m 3 m −3 for 0–160 cmsoil depth. Estimated productive water flow as plant transpiration was low, amounting to 4%–9% of the available water for the non-fertilised crop and 7%–24% for the fertilised crop. Soil evaporation accounted for 31%–50% of the available water, and showed a low variation for the observed range of leaf area (LAI <1m 2 m −2). Deep percolation was high, amounting to 200–330 mm for the non-crusted surfaces, which exceeded soil evaporation losses, for 1994–95 with relatively high annual rainfall (517–596 mm). Even a year with lower rainfall (488 mm) and a distinct dry spell during flowering (1996), resulted in an estimated deep percolation of 160 mm for the non-fertilised crop. The crop did not benefit from the additional inflow of runon water, which was partitioned between soil water storage and deep percolation. The only exception to this was the fertilised crop in 1996, where runon somewhat compensated for the limited rainfall and the higher water demand as a result of a larger leaf area than the non-fertilised crop.The effects of rainfall erraticness, resulting in episodic droughts, explain why a crop that uses such a small proportion of the available water, in an environment with substantial deep percolation, still suffers from water scarcity. Application of small levels of phosphorus and nitrogen roughly doubled yields, from 380 to 620 kg ha −1, and plant transpiration, from 33 to 78 mm. Evapotranspirational water use efficiency ( WUE ET) was low, 6500–8300 m3 ton-1 grain for non-fertilised crop,which is an effect of the lowon-farmyields and high non-productive water losses. The estimated seasonal rainfall partitioning indicates the possibility of quantifying vertical water flows in on-farm environments in the Sahel, despite the presence of surface overland flow.