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The viability of arbuscular mycorrhizal fungi (AMF) spores formulated with biochars derived from the pyrolysis of raw (ROP) or impregnated olive pomace with olive mill wastewaters (IROP) was investigated under laboratory-controlled conditions. A greenhouse experiment was also conducted to study the effect of AMF spores and biochars adding on the growth of maize plants. Nine treatments, combining one biochar (ROP or IROP) at a level of 2.5 g/kg of soil and inoculation or not with Funneliformis mosseae at two concentrations (30 and 125 spores/kg of soil), were arranged in an entirely randomized block design. The results of the formulation trial showed that arbuscular mycorrhizal fungi (AMF) spores had short-term viability and are sensitive to the presence of biochar. This effect is more pronounced when the biochar is made from IROP. Both the AMF and biochars treatments did not significantly enhance the growth of maize plants, biomass production, and leaf chlorophyll contents. However, the most significant effect on nutrients uptake was observed in the modalities treated with AMF alone (30 spores/kg of soil) and AMF combined with the biochar made from IROP (IROP $+$ 30 spores/kg of soil). In those modalities, the N uptake was improved by 45% and 33%, respectively. Moreover, biochar addition to the soil did not particularly enhance root colonization by AMF and no negative effect of its application was observed either. However, the inoculation of spores enhanced propagules production and maize root colonization.

The essential oils of the widely distributed boreal/Arctic dwarf shrub, Rhododendron tomentosum ssp. subarcticum (Harmaja) G.D. Wallace, have important ecological, cultural, medicinal, and commercial roles. To understand the relationship between resource limitation and essential oil content of this species we measured the amount and diversity of terpenes from shoots of plants exposed to a 14-year ecosystem resource manipulation experiment in Arctic Alaska. Treatments tested interactive effects of nitrogen (N) and phosphorus (P) addition, warming and N + P fertilization, and shading and N + P fertilization. The controls and NP fertilization had the highest essential oil content, whereas shading and P addition had less than 20% of the control content. Warming reduced essential oil content to

Rapeseed meal (RSM) is known for its high nutritional quality as animal feed. However, there has been little studies on the effect of nitrogen fertilization on RSM chemical composition, mainly neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and ash content. Therefore, this study was carried out to evaluate the effect of nitrogen application rate on chemical composition of RSM in interaction with different spring rapeseed varieties (Brassica napus L). A field experiment was conducted during 2018/19 cropping season at the experimental station of the Ecole Nationale d’Agriculture de Meknès” according to a split-plot design with three replications, using six nitrogen application rates, as main plot, and six rapeseed varieties, as subplot. After seeds harvest and oil extraction, meals derived from the different treatments were used in this study. Results showed that increasing nitrogen rate from 0 to 120 kg N ha−1 led to a significant rise in meal yield up to 74.58%. A positive effect of nitrogen fertilization was observed on dry matter, protein content and ash content, recording the highest values at 120 kg N ha−1 treatment. However, cellulose and lignin content were affected negatively by nitrogen fertilization. The nitrogen supply of 150 kg N ha−1 resulted in a reduction of ADF and ADL contents by 23% and 28%, respectively, compared to the unfertilized control (N0). Variability within rapeseed varieties for all parameters except dry matter and ADL content was highlighted.

Research on elephant grass with 2 x 2 factorial repeated five times has been carried out at AGRO-1 and AGRO-2, Tuntang watershed. Observed variables were: plant height, forage production, dry matter content, crude protein, crude fiber. Soil samples were observed including soil bulk density, pH, and total N. Plant height in AGRO-1 was higher (85.1 cm) than in the AGRO-2 system (71.5 cm). Season affects plant growth as indicated by lower plant height in the dry season (66.8 cm) than in the rainy season (89.8 cm). The AGRO-1 system has a better forage yield than the AGRO-2 system. Forage dry matter varies between agroforestry systems and seasons. The lowest DM is in the rainy season at AGRO-1. Crude protein in AGRO-1 is lower than in AGRO-2. The highest protein content in AGRO-1 in the rainy season (11.3 %), the lowest in AGRO-2 in the dry season (6.0 %). The crude fiber of elephant grass in AGRO-2 is higher than in AGRO-1. The crude fiber content in the dry season is higher than in the rainy season. The conclusion of this study was that elephant grass in AGRO-1 had better growth, production, and quality than in AGRO-2.

Taking into account plant biological properties, soil properties, soil-climatic conditions, and fertilizer properties, the development of the optimal rate, duration, and methods of application of suspensions made from mineral fertilizers, the optimization of the soil nutrient environment, the formation of the necessary chemical composition in the plant, and scientific research aimed at managing plant nutrition, special attention is paid. In Uzbekistan, scientific research aimed at evaluating the effective use of mineral fertilizers in increasing the yield of agricultural crops, including wheat, is being conducted, and certain results are being achieved. It is critical to develop an optimal system of using mineral fertilizers to ensure the cultivation of high-quality grain crops from autumn wheat varieties in the irrigated typical gray soils of the Tashkent province, as well as to determine the nutrient environment formed in the soil during specific periods of autumn wheat development phases and the amount and ratio of nutrients in the plant. Fertilizer is an effective and fast-acting factor that increases the quality of the crop. Therefore, it is important to develop the optimal norm for using a suspension of mineral fertilizers in foliar feeding, taking into account the characteristics of the soil and variety, to grow a high-quality grain crop from wheat, as well as to study the effect of these norms on the growth development, seedling thickness, grain yield, and quality of autumn wheat.

Macronutrients are very important in plants, because they have a significant role in the development of lants and very required to fulfill. Nitrogen, Potassium, and also Phosphorus are three important macronutrients. Bio seeding block is a seeding media made by soil block, it consists of a sugarcane waste. It is good for an environment, sensible, and rich in natural matters. The aims in this research, is to analyze the nutrient composition in bio seeding block. Bio seeding block products used waste from sugarcane, that consisted of bagasse, sugarcane filter cake, and ash from sugarcane. There are 4 treatments to analyze bio seeding block such as : Treatment A, with ratio between sugarcane filter cake : bagasse : and ash are 4 : 4 : 1, treatment B, with ratio are 5 : 3 : 1, treatment C, with ratio are 6 : 2 : 1, and treatment D, with ratio 7 : 1 : 1. The results show that the highest amount of N is in treatment D that is 0,439; the highest amount of P is in treatment B that is 2,170; and the highest amount of K is in treatment A that is 0,480. Based on plant growth tests (plant height, leaf width, and stem diameter) show that medium A is the fastest growing medium in the first 15 days and also has high number of main nutrients.

This article is one of the only long-term scientific experiments in Central Asia, which has been conducted for 96 years since 1926 at the Scientific Research Institute of Cotton Breeding, Seed Production and Agrotechnology in Kibray district of Tashkent region. Option 1 monoculture, 30 t / ha fertilizer per hectare + 30 kg / ha phosphorus per year, Option 2 monoculture, N P K 250:175: 125 kg / ha per year and Option 3 monoculture, absolute fertilizer, control options humus content 96 analytical scientific data on changes during the year. In the article, the highest decrease in humus content was observed in the control variant where was not used fertilizers, the amount of humus after 20 years was 21.4% or 11.4 t / ha compared to the initial amount, after 40 years it was 30.9% or 16.46 t / ha, after 60 years it was 35.7% or 19.05 t / ha, after 80 years it was 49.3% or 26.29 t / ha, and 54.3% or 29.17 t / ha after 96 years, this indicator is 12.2% -6,487 t / ha. In the experiment, the highest rate of humus reduction for 96 years was 54.3% in the control variant, 30 t / ha of manure + 25 kg / ha per year in P2O, 47.5% in variant 1, N P K 250:175:125 kg / year. The norm was found to decrease by 36.9% in variant 2, where the norm was applied.

A new type of micronutrient liquid fertilizers was obtained by treating the calcium nitrate porridge obtained on the basis of research with urea (ammonium nitrate, KAS) and micronutrient (Cu Zn Co) salts in the amount necessary for plant growth. The chemical composition, product properties and rheological properties of liquid fertilizers containing microelements were studied, and a laboratory device for the production of liquid fertilizers was created. As a result of preliminary investigations, it was found that copper, zinc, molybdenum, manganese, calcium, magnesium are the most scarce trace elements in the soils of our republic. In order to apply microelements to the soil as fertilizers, the research was carried out in order to find their various sources, to study various industrial residues, to solve the problems of testing, processing of local raw materials and industrial waste containing trace elements a rational technology for obtaining new types of simple and complex liquid, granular and suspended fertilizers was developed, and its agrochemical properties and the amount of microelements in the plant composition and its effect on the absorption of nutrients (NRK), cotton yield and quality parameters of fiber were determined when used in typical gray soil conditions.

The aim is to increase the mobile nutrient content in the soil by applying optimal nitrogen and potassium fertilizers without the use of phosphorus fertilizers on irrigated typical gray soils moderately supplied with mobile phosphorus. Significant differences are observed in the amount of mobile phosphorus in the soil from the beginning and till the end of the vegetation. It ranged between 24.28-27.15 mg / kg in the driving layer and between 15.20-19.05 mg / kg in the sub-driving layer. The amount of N-NO3 increased during the vegetation to 29.1-34.4 mg / kg in the driving layer, N-NH4 in the driving layer changed to 3.1-4.2 mg / kg. Exchangeable potassium was found to fluctuate between 148.72–177.82 mg / kg in the driving layer at the end of the vegetation period and varied between 179.2–182.75 mg / kg in the sub-driving layer.

Abstract The effect of anomalies of foliar mineral nutrients on the nutritional behavior of apple crops has been evaluated using parameters obtained by means of remote sensing techniques. Twenty-five plots in commercial orchards were selected in the five most important municipalities of Chihuahua State, Mexico in which the main nutritional parameters were measured (N, P, K, Ca, Mg, Fe, Zn, Mn, Cu, and B). Important deficiencies of these nutrients were detected in 88% of the analyzed crops. These deficiencies showed significant correlation with the spectral data (SPOT5) and with the NDVI elaborated from these data. The mathematical models obtained showed high determination coefficients for most of the mineral elements; concretely, nitrogen and calcium presented the best results (0.80 and 0.76, respectively). Resumen Se ha evaluado el efecto en las anomalías de los nutrientes minerals foliares en el comportamiento nutricional de los cultivos de manzanos utilizando parámetros obtenidos mediante técnicas de teledetección. Se seleccionaron veinticinco parcelas en fincas comerciales de los cinco municipios más importantes del estado de Chihuahua (México), en los que se midieron en campo los principales parámetros nutricionales (N, P, K, Ca, Mg, Fe, Zn, Mn, Cu y B). Se detectaron importantes deficiencias de estos nutrientes en el 88% de los cultivos analizados. Estas deficiencias mostraron una correlación significativa con los datos espectrales (SPOT5) y con el NDVI elaborado a partir de estos datos. Los modelos matemáticos obtenidos proporcionaron altos coeficientes de determinación para la mayoría de los elementos minerales; concretamente, el nitrógeno y el calcio presentaron los mejores resultados (0.80 y 0.76, respectivamente).

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The management of soil organic matter, an important issue in reducing nitrate leaching to groundwater. Description of the subject. The nitrate concentration in half of the groundwater bodies of the Walloon Region (Belgium) has justified their classification as vulnerable zones under the Nitrates Directive (ND). This vulnerable area has a relatively high diversity of agro-soil environments. Thus, the nitrogen content of agricultural soils can vary locally by a factor 4. Objectives. This study aimed to establish whether the carbon content of a soil is a significant risk factor in nitrate leaching to groundwater. Method. The article is based on measurements of nitrate nitrogen residue (APL) and soil total organic carbon (TOC) at the beginning of the leaching period. The measurements were made in 2012 in 1,500 plots, during inspections organized by the Wallonia Public Service. This was as part of the application of the Program for the Sustainable Management of Nitrogen in Agriculture, the scheme for implementing the ND within the Walloon region. Results. Examination of the results showed both that the APL was positively correlated to the TOC and that plots with "noncompliant" APL results had a significantly higher average TOC than the other plots. Conclusions. Since APL is an environmental indicator of the risk of nitrate leaching, it appears that the TOC may constitute a risk of groundwater contamination by nitrate. It is therefore advisable to improve the inclusion of this parameter in advice regarding nitrogen fertilization and secondly, in the case of summer harvest, to better manage the sowing of catch crops.

The purpose of the study is to determine the suitability for making sound decisions on the reproduction of soil fertility of the following quantitative laws of the methodology for managing material and energy flows in crop rotations: the energy content of 1 ton of humus (in GJ) is equal to half the nitrogen contained in it (in kg); the amount of exchangeable energy (in GJ) in 100 kg of phytomass is equal to the halfsum (in kg) of nitrogen and phosphorus pentoxide (about 2/3 of it falls on nitrogen). The approbation was carried out on the data of long-term stationary experiment. The results are as follows: with an increase in the level of fertilizer, nitrogen removal with the yield increased by 30–40%, and that of phosphorus by 6–12%; due to doubling the manure rate and the use of mineral fertilizers, the phosphorus balance became positive, and the nitrogen one remained negative, but improved by 17–28% depending on the type of a crop rotation. The deviation of the calculated balance of the exchangeable energy from the actual one on the poorly and most richly fertilized backgrounds was -5.5 to -11.9% and 3.0 to 8.6%., respectively.

In Ecuador, oil palm plantations from the Quinindé-Quevedo region are subject to El Niño/Southern Oscillation (ENSO) with a preponderance of La Niña weather conditions. With more than 2,000 mm, the total annual rainfall is theoretically non-limiting but, with only 1,000 h, the total annual sunshine is well below the 1,800 h minimum recommended. Starting in the 1970s, the frequent occurrence of frond yellowing symptoms in the region became a recurrent worry for growers, convinced that they were facing the expression of a mineral deficiency. In this study, we used experimental results to examine the actual role of mineral nutrition in yellowing manifestation. We described the effects of two El Niño events (1982/1983 and 1997/1998) on climate variables and analysed their putative consequences on palm physiological functioning that could explain the observed foliage recovery. Our analysis led us to conclude that a direct mineral deficiency was not involved, as the soil reserves for the main nutrients were not to blame. We rejected the most frequently proposed hypothesis, whereby yellowing is caused by magnesium deficiency. Our study revealed the key role played by nitrogen, the best indicator of yellowing. Variations in N status appear to be linked to the same factors that determine the symptoms and we opted for the hypothesis of physiological disruption generated by low solar radiation levels under normal conditions. The study also reveals the need to consider specific optimum contents for N and Mg and to adjust fertilizer recommendations to local climate conditions.

Impact of Soil Fertility Management Practices and Cropping systems on Nitrogen Nutrition and Yields of Millet (Pennisetum glaucum (L.) R.Br.) in Niger. To identify the best methods of soil fertility management in Sahel conditions, the following objects were compared in a trial conducted according to a Latin square arrangement from 2011 to 2013 at Kalapaté (Niger) in three different millet-cowpea cropping systems (monoculture, intercropping, and rotation): (i) control without manure application, (ii) micro-dose of NPK (6 g of 15-15-15) per hole + 30 kg N ha-1, (iii) rock phosphates (30 kg ha-1 P2O5) + 30 kg N ha-1, (iv) phospho-compost (5 tones ha-1) + 30 kg N ha-1 and (iv) Super Simple phosphate (30 kg P2O5 ha-1) + 50 kg N ha-1. 15N isotope marked NPK and urea were used to assess the contribution of organic and mineral fertilization and of cowpea cultivation to the Nitrogen nutrition of millet. Millet yields of the treatments were significantly different from the control with yield increases ranging from 116 to 299%. Cowpea-millet rotation associated with these technologies led to a mean increase in grain yield of millet varying from 40 to 112% compared to monoculture. The use of the 15N isotope method evidenced the major role played by crop rotation in Nitrogen removal and uptake from the soil. The average Land Equivalent Ratio (LER) calculated from all compared crop associations amounts to 1.46. This indicates that it is more advantageous to practice intercropping than monoculture. Therefore these technologies improve agricultural productivity by enabling efficient use of land and better mobilization of soil nitrogen.

Introduction. Interacting soil organisms support biological processes that participate in soil functions, organic matter decomposition, and nutrient cycling. Earthworms and microorganisms play a range of beneficial roles in agricultural systems, including increased organic matter mineralization, nutrient cycling, and soil structure stabilization. Literature. The following aspects of crop residue management effects are examined in this paper: (i) earthworm composition and structure; (ii) soil microbial communities; and (iii) phosphorus (P) and nitrogen (N) element availability and distribution in the soil profile. Conventional tillage (ploughing) is often reported to generate decreased soil organism abundance and diversity, primarily earthworms and microorganisms, as well as a uniform distribution of the nutrients P and N within the ploughed soil horizon. Soil residue incorporation of mineral particles can maintain P and N levels, however returning soil also increases aeration and the activation of microbial activity. Hence, comparisons of tillage effects on soil biological functioning and nutrient cycling remain unclear. Conclusions. This review highlights the challenges in establishing definitive evidence regarding the effects of crop residue management on soil organisms and nutrient dynamics. The studies examined reported variability in soil and climate, and the complexity of soil processes contributed to the absence of clear findings. Further research is required under temperate climate conditions.

Effect of management of pruned fronds of oil palm on soil carbon stock and soil physico-chemical properties in Beninese smallholder plantations. Description of the subject. In Benin, oil palm plantations are widely managed by smallholder farmers. The study addresses the impact on soil properties of the recycling of pruned fronds from these trees. Objectives. The study aims to assess the effect of two modes of management of pruned fronds on the carbon stock and physico-chemical properties of soil. Method. Six oil palm plantations were selected to represent two age classes (7-12 years and 13-24 years) in southeastern Benin. They were used to compare the soil properties of two areas: the areas of total recycling of pruned fronds (TR) and the areas of no recycling of the fronds (NR), which represented the control. In each plantation, soil samples were collected under the two treatments, from holes of up to 50 cm depth, near six oil palm trees. The soil properties were determined using conventional laboratory methods and near-infrared spectroscopy method. Results. Carbon and nitrogen stocks under TR of adult plantations were 58 Mg·ha-1 and 4.3 Mg·ha-1, respectively, and were significantly higher than the stocks in all other treatments (34.6 Mg C·ha-1 and 2.9 Mg N·ha-1). Recycling of pruned fronds improved soil fertility at a depth of up to 20 cm in the adult plantations. The porosity and bulk density of the soil were also improved. Conclusions. The management of the pruned fronds in the smallholders' oil palm plantations modified the soil properties, which were significantly improved in the top soil after 10 years of frond recycling.

Climate change is having profound influences on Arctic tundra plant composition, community dynamics, and ecosystem processes. Stoichiometric homeostasis (H), the degree to which a plant maintains its internal nutrient concentrations independent of nutrient variations in its environment, may be a useful approach to predict the impacts of these influences. In this case study, we used fertilization manipulation data to calculate homeostasis indices based on nitrogen (HN), phosphorus (HP), and nitrogen to phosphorus ratios (HN:P) of aboveground tissues for seven common tundra vascular species belonging to three growth forms. We then analyzed species H relationships with dominance, spatial stability, and responsiveness to various experimental manipulations. Each of the H indices was correlated amongst tissue types within each species and was generally highest in ericoid mycorrhizal host species and lowest in the ectomycorrhizal birch. Species HP and HN:P were consistently positively correlated with aboveground biomass within the controls and across all manipulations. Furthermore, these same species were spatially stable across experimentally warmed field plots. Stoichiometric homeostasis theory has been successful in predicting grassland community dynamics. This first test of its applicability across a variety of Arctic plant growth forms highlights its considerable potential in predicting tundra plant community structure and responses to environmental change.

At high temperatures under oxidizing environments, titanium-based alloys form an oxide scale and dissolve large amount of oxygen in their metallic matrix. Oxygen dissolution is a cause of embrittlement. Nitrogen is a secondary oxidant, which also dissolves in titanium during oxidation in air. Oxidation experiments of Ti-6Al-2Sn-4Zr-2Mo-0.1Si titanium-based alloy at 650 °C for 1000 h in synthetic air (20%O2- 80%N2) and in a mixture of 20%O2-80%Ar, showed that nitrogen reduces both oxide scale growth and oxygen dissolution. Atom probe tomography revealed that nitrogen effect is due to the formation of an interfacial layer of nitride Ti2N but also to the formation of a nitrogen rich a-Ti-based solid solution, which both act as difiusion barriers for oxygen because of their low oxygen solubility.

This investigation was carried in Hadjadj mahmoud farm (El-Menia) during 2008/2009 to study the effect of P sources [Single super phosphate (SSP) P 20 and Fosfactyl NP 3:22] and P levels (30, 60, 90 and 120 kg.ha -1 ) on wheat (Triticum durum Desf. Var. carioca). The results obtained show that the SSP fertilizer yielded the best yields of grain, biomass and nitrogen contents of the aerial part, regardless of the stage of cultivation, end tillering stage, flowering and maturity compared to fosfactyl. The optimal dose favorized the best grain yield, N content of the whole plant and grain at maturity. Positive correlations were recorded between the dry matter produced at the maturity stage and the N-content of the leaves at the end tillering stages (0.558 ***) and flowering (0.546 **) on the one hand; and negative at maturity stage (-0.25ns) on the other hand. [ABSTRACT FROM AUTHOR]

Prospects for improving the provisional nitrogen fertilization recommendation at field scale in Wallonia using the AzoFert® software. The French software AzoFert® for nitrogen fertilization recommendation is currently under adaptation and validation for soil and climatic conditions in Wallonia by the CRA-W within the INTERREG IV project "SUN" (Sustainable Use of Nitrogen). This adaptation has raised the need for a change of values in the parameter tables and catalogs relating to meadow residues, crop residues, catch crop practices, crops, organic amendments and soil type. Data from 25 trials of increasing nitrogen fertilizer rates conducted by CRA-W between 1996 and 2011 in cereal, potato and vegetable crops located on loam and sandy loam soil were used to validate the AzoFert® software adapted for Wallonia. The difference between nitrogen rates recommended on the one hand by AzoFert® or Azobil® (software currently used in the reference lab for Nitrate [Requasud] at CRA-W) and the optimal dose of nitrogen fertilizer assessed in each trial on the other hand shows that, in most cases, AzoFert® gives a recommendation closer to the optimum than Azobil®. The nitrogen uptake measured in the plants collected in the unfertilized control plot also shows a higher correlation with nitrogen supply from the soil assessed by AzoFert® than for plants assessed by Azobil®. The more accurate estimate of the mineralization of organic sources, probably linked to the dynamic soil nitrogen supply approach integrated into AzoFert®, may explain the gain in the greater accuracy of the AzoFert® recommendation in comparison with that of Azobil®.

Impact of the destruction of grassland on soil nitrogen residue and the management of nitrogen fertilization. When permanent grassland is destroyed, the mineralization of organic matter accumulated in the soil leads to a substantial enrichment of soil mineral nitrogen for several years after the destruction occurs. Results show that, following the destruction of grassland in early spring, yields of maize silage were high for a period of two years. Furthermore, residual nitrogen in the soil after harvest far exceeded the expected values for the crop. Results from other studies show that the risk of nitrogen loss is high following the destruction of permanent pasture before winter even in colder climates. Reducing the risk of nitrogen loss between two cultures requires not only a more accurate control of fertilization by carrying out soil analyses, but also the application of a generalized ban on grassland destruction before winter and the carrying of appropriate crop sequences to remove nitrogen available in large quantities over as long a period as possible.

Sustainable use of nitrogen beyond the single "nitrate" issue. The aim of the sustainable management of nitrogen is to reduce dramatically the risk of nitrogen leaching into groundwater. Regulations and recommendations have resulted in a more judicious use of manure as a mineral fertilizer to benefit both the environment and farmers. Rehabilitating leguminous plants into our rotations and our forage areas needs to become a priority. These plants can partially substitute for imported soya and, at the same time, synthesize the free nitrogen available to plants. Management of intercropping and in particular of catch crops can no longer be limited to the single issue of nitrate in water. Integrated crop protection and risk reduction of greenhouse gas emissions also need to be taken into account and flexibility needs to be incorporated into the implementation of these intercropping rules.

Efficiency and fate of slurry N applied to permanent grass in Ardenne (Belgium) – Effect of the choice of spreading period. In Haute Ardenne and Pays de Herve, areas devoted to grass, slurry represents the main source of nitrogen; slurry is applied on permanent pasture. This paper aims to compare the nitrogen efficiency of cattle slurry with that of mineral fertilizers and to determine the influence of the choice of spreading period on N use by grasses. Results from two long terms trials and from one in micro plots using stable 15N are presented. Results show that the fertilizers applied (organic and mineral) only affected at a mean level of 25% N absorbed by grassland. The efficiency of spring slurry applications carried out in favorable spreading conditions matched those of mineral N. From our results, it can be concluded that N losses in grasslands are very low and are due to volatilization just after the spreading of slurry.

Nitrogen fertilization management of open-field crops. Opportunities for improvement of nitrogen use efficiency based on crop nitrogen status monitoring. The improvement of nitrogen use efficiency in crops is currently an important issue in farming due to current and future economical and environmental constraints. Splitting of N fertilizer application is the most suitable approach for providing an optimal match of N need and supply. The implementation of monitoring methods to assess crop N status is required to define the relevant amounts and periods required for split applications. This paper discusses the available methods of split N fertilizer application and their mode of use and implementation. After a short overview of the concept of crop N status, the main existing methods to estimate nitrogen needs are examined for their accuracy, specificity and sensitivity based on research conducted at CRA-W (Production and Sectors Department, Crop Production Systems Unit) over the last two decades, focusing specifically on the potato crop. The methods and the results described relate to the petiole sap nitrate concentration test assessed via a reflectometer, the measurement of leaf chlorophyll concentration with a handheld chlorophyll meter, leaf chlorophyll fluorescence readings with handheld fluorimeters, and the measurement of crop light reflectance with a handheld radiometer (ground-based remote sensing) or with satellite imagery (spatial remote sensing). Conditions for implementing such methods within decision support systems are briefly described, by focusing on the need to use relative values rather than raw values taken from the readings, and also on the requirement for threshold value definition. The integration of crop nitrogen status values into N fertilization recommendation models is illustrated through a Decision Support System created at CRA-W for the potato crop.

Evaluation of intermediate crops to trap nitrogen and produce forage. Experiments on catch crops were carried out over a period of three years in the loamy region of Belgium at the Catholic University of Louvain. The results were used to evaluate the performance of certain species of grass and legume, in pure or mixed culture. The performance of each species was judged according to its ability to take up nitrogen (catch crops), to produce forage of a sufficient quality and to meet certain agronomic criteria for intercropping. The results showed that grasses in pure culture or when mixed with legumes were able to significantly reduce soil nitrogen at the beginning of the drainage period, provided that the proportion of non-legumes constituted at least 50% of the mixture. Biomass produced by most of the tested crops can be harvested as complementary forage, which can be useful in times of shortage.

Evaluation of the third Action Programme. Recommendations for regulatory and scientific research. In accordance with the Nitrates Directive, the third "Durable Nitrogen Management Plan" (PGDA) will be soon reviewed in Wallonia (Belgium). The second "Nitrate – Water" workshop took place between 28th May and 1st June 2012. The workshop was attended by both Belgian scientists (Université catholique de Louvain - UCL, Walloon Agricultural Research Center CRA-W, Université de Liège - ULg, Gembloux Agro-Bio Tech) and French scientists (National Institute for Agricultural Research - INRA). In the light of the results of experiments presented by scientists at this workshop, modifications to the PGDA are now recommended. These concern organic and mineral nitrogen fertilization for crops and meadows; catch crops; soil nitrate-nitrogen residue limitation in autumn, at the start of the nitrate leaching period; the management of meadow ploughing and a modification of the dairy cow standard for nitrogen production.

Improvements after precision dietary management of nitrogen rejection in two commercial dairy farms in Wallonia. Two dairy farms located in Pays de Herve and in Ardennes were followed at regular intervals in order to assess levels of nitrogen rejection. In Farm 1, the cows were divided into two groups: group HP contained high production cows and group BP contained cows with a lower production yield. Each group was offered a specific basal diet. In Farm 2, only one group of cows was assessed. The feed rations on both farms were characterized by a imbalance between the yields allowed by the energy or the nitrogen supplies and by an extremely high OEB balance of 794, 582 and 726 g, respectively, in groups HP and BP and in the Farm 2 group. Dietary changes were proposed in order to balance milk yields and to reduce the hypothesized nitrogen balance. The yield and urea content data from each milk record, along with data regarding nitrogen rejection, were statistically analyzed using a mixed model, which included an autoregressive covariance. The data from records 2, 3, 4 and 5 were then compared to the data from record 1. The advised changes implemented in the feeding management plan maintained milk yields at values similar to the yields observed in record 1 – 36.2, 24.3 and 23.0 l of 4% fat-corrected milk expressed for fixed days in milk produced by groups HP and BP and the Farm 2 group. The changes induced a significant reduction in the milk urea content (220 vs 300 mg·l-1) and a significant reduction in nitrogen rejection, whether expressed in terms of g per day per cow, g·l-1 or kg per year per cow. The cows in the Farm 2 group rejected less nitrogen in absolute terms (217.9 vs 260.1 g per day). However, it is interesting to note that the management approach in Farm 1 was more efficient in terms of nitrogen rejection since the level was on average 9 g·l-1 in comparison with 10 g·l-1 in Farm 2. In conclusion, it appears that, for either farm, whether an intensive or extensive management regime was being employed, the provision of well balanced feed rations led to a reduction in nitrogen rejection. It should, however, be noted that management advice needs to be provided on a farm by farm basis.

Impact of cattle stocking rate, under grazing, during autumn on potential nitrogen leaching: reference values established in the south-east of Belgium. Grassland, which accounts for half of the agricultural area in Wallonia, forms the basis of many ecosystemic services: cultural, grass production, regulatory services, etc. Nevertheless, the poor ability of cattle to fix ingested nitrogen leads to significant N rejection during grazing. N is excreted in concentrated form via urine, and thus becomes unevenly distributed within the paddock. This phenomenon increases the risk of N leaching in grazed grasslands, especially if urine deposit occurs later during the grazing season, in the autumn. It is therefore necessary to specify good livestock management practices, with particular reference to the livestock stocking rate to be applied during autumn grazing. This ensures the reconciliation of both animal and environmental performance. With this aim, a study was performed over a five-year period, during the autumn, to test the impact of the livestock stocking rate on the risk of nitrate leaching in grazed grassland, in the Jurassic area of south-east Belgium. A gradient of stocking rate was established, ranging between 150 and 350 BLU grazing days·ha-1. Results underlined a highly significant impact of the "year" factor on potentially leached nitrogen (APL), ranging between 9 (2010) and 23 (2005) kg of N-NO3-·ha-1. The impact of the stocking rate was only marginally significant. Whatever the year or the stocking rate, the recorded APL level never represented a significant risk to water resources, and this was in spite of a relatively high stocking rate at the end of the grazing season. This low impact of the stocking rate could be explained by the type of cattle (beef breed heifers and dry cows) mobilized in order to apply these end-of-season stocking rates. A further explanation could lie in the addition of hay to the cattle's diet in order to achieve the highest stocking rates. Higher level of APL would be expected under grazing with dairy cows.

This article focuses on the interest in improving the nitrogen use efficiency of rapeseed varieties in France. We show that this trait is of interest at different levels of the value chain and for different markets. Nitrogen use efficiency improves farmers’ margins by reducing fertilizing costs or increasing yields. Nitrogen use efficiency also improves the GHG (greenhouse gas) balance of rapeseed used for biodiesel production and the image of edible rapeseed oil for consumers within the framework of specific labels. Finally, nitrogen use efficiency can also be seen as a trait that improves the protein content of rapeseed oilcake and, therefore, increases its value compared to competing sources of protein. After a detailed presentation of these different valuations, we provide current or possible measures that have been or could be implemented to encourage different actors in the sector to develop and diffuse this trait.

Influence of the fertilization type, the day in the paddock and the month on nitrogen rejections in dairy cows. The present study aims to quantify nitrogen (N) rejections in dairy cows on a rotational grazing system with different types of fertilization (compost, slurry and mineral N) at two different days in the paddock (days 3 and 5) and during two different periods (June and September). Grass yield and height were measured along with the chemical composition. The live weight was recorded when the cows moved into the paddock and milk yields was recorded at each milking. N intakes were measured on the basis of the energy requirement. When the cows were in the paddocks, individual samples of faeces and urine were collected to assess N rejections. The urea content in milk from the tank or from the individual cows was also measured. N intake was higher on day 3 than on day 5 and in September as compared with in June but was not influenced by the fertilization. The amount of N produced in milk was not influenced either by the fertilization, by the day on the paddock or by the month. The amount of urinary N was significantly higher in the N mineral group than in the two other groups. The N excretion in faeces and urines was higher on day 3 than on day 5. In June, the N excretion by the urine was lower than in September while the N excretion by the faeces was higher. Equations were calculated in order to estimate the N excretion by the urine in grazing dairy cows from the urea content in milk of a group of cows.

Relationship between evolution in the agriculture and in the water quality from 1950 to 2000. In 1991, Europe has adopted the Nitrates Directive to reduce the impact of agriculture on water nitrate pollution. Nitrate concentration in groundwater has not always been so worrying as it was at the end of the ’80. Working on the revision of Action Programme, it is usefull to list changes in agriculture during the two decades before the degradation of water quality. So, with regards to land use, we observe a huge decrease of grassland cover and an increase of maize surfaces. Livestock has highly increased during this period. Finally, use of nitrogen (mineral and organic) has increased out of proportion to the yield increase. Following this analyze, loss of grassland cover should be at least stopped, nitrogen supplies should strictly correspond to crop needs, taking into account the soil restitutions.

Evaluation of the catch crops efficiency in November. The walloon Action Programme (Belgium) called “Sustainable Use of Nitrogen’s Programme”, plans the ploughing in of the catch crops from the 1st December. However it would be preferable for agronomic reasons (to make the ploughing easier, to avoid grains production) to plough in the catch crops from 15th November. Five years (from 2002 to 2006) measurements of soil nitrate residue have nevertheless underlined the interest of maintaining this cover up to 1st December; some 10 kg N-NO3 -.ha-1 were consummed by the catch crop during the end of November.

Evaluation and revision proposal of the second Action Programme in Walloon Region (Belgium). In accordance with the Nitrates Directive, the second “Durable Nitrogen Management Plan” (PGDA) will be reviewed in 2010. In the light of scientist experiment’s results exposed at the workshop “Nitrate-Eau” held in Peyresq (2 to 5 June 2009), modifications of the second programme are recommanded. These deal with organic and mineral nitrogen fertilisation for crops and meadows, catch crops, soil nitrogen residue controle at the beginning of the nitrate leaching period, meadow’s ploughing management and the dairy cow’s standard for nitrogen production.

Stable 15N isotope and lysimeter, complementary tools in order to study the nitrogen leaching in agricultural soils. Stable 15N was used in lysimetric trials conducted with the aim to study nitrate leaching of agricultural soils. At Gembloux, a rate of 200 kg N.ha-1 as 15NH4 15NO3 with an isotopic abundance of 2.161 At%15N was applied in two lysimeters before a spinach crop, followed by beans and winter wheat; in the first lysimeter, total recovery by crops was less than 39.8% while in second lysimeter, recovery was 62.2%. Concentrations of N-NO3 - in leached water were always higher in lysimeter 2 than lysimeter 1, probably due to less microbial immobilization of nitrogen. At Remicourt and Omal, a simulated mineral residue of 150 kg N.ha-1 (rate of 15NH4 15NO3 applied in autumn) has completely disappeared from the soil profile (0-90 cm) already in July of the following year. At Omal, a winter crop has recovered no more than 9% of nitrogen rate applied in autumn. Measurement of N-NO3 - concentration in leached water has shown clearly higher levels at Remicourt (even more than 70 mg N.l-1 probably caused by an application of high rate of compost rich in nitrogen) than is Omal. Stable 15N isotope could not be analyzed in leaching water probably due to a leak of sensitiveness of the analytical equipment.

Towards a revison of the dairy cow’s standard for nitrogen production: justification and what are consequences for soil link rate of dairy farms. At present, the dairy cow’s standard of nitrogen production in Walloon region is 90 kg per year. This standard is used to calculate the “soil link rate” of farms, a balance between the organic nitrogen to be spread on land and the quantity legally authorized considering grassland and arable land area. This standard is appreciably lower than that fixed by other member states and was criticized by the European Commission during the negotiations having ended in the second program of sustainable nitrogen management. Further to new studies, it seems that the gaseous loss of nitrogen averages in buildings and during the storage is weaker than the 15% value which was used to justify this 90 kg standard. It also seems that there are big differences of average dairy production and average rate of urea according to the agricultural regions and consequently that regional production standards correspond better to the reality. On basis of these mean values, the dairy cow’s annual productions of nitrogen vary between 81 kg per year in grassy region of Fagne and 99 kg per year in Haute Ardenne and in grassy region from Liege. For the Walloon region in general, the average production is 94 kg per year. The adoption of different values of dairy cow’s nitrogen production by region would lead to an increase of 8% of the soil link rate of dairy farms in Haute Ardenne and of 7% in grassy region from Liege and a decrease of 7% in grassy region of Fagne.

For the successful cultivation of most undomesticated fruit trees such as shea butter tree (Vitellaria paradoxa C.F.Gaertn.), there is a need to identify their nutrient requirements and optimal growth conditions. Responses of shea seedlings to combined N and P fertilization, and to inoculation with arbuscular mycorrhizal (AM) fungi was investigated. Six months old shea seedlings were transplanted into pots and grown for six months using a sterile nutrient-deficient soil. The seedlings were inoculated with the AM fungus Glomus intraradices Schenk & Smith. The fertilization treatments consisted of a factorial combination of three levels of N supplied as NH4NO3-N and P supplied as Ca(H2PO4)2. Fertilization stimulated plant height, collar diameter and dry weights (DWs) compared with non-fertilized treatments. These improvements were associated with an increase in total shoot N and C uptake (33% increase) whereas P and K contents were not affected. There was significant N x P interaction on DWs and total shoot N and C contents, suggesting that seedling N responses were influenced by P rates. Consistent N responses in DWs, and total shoot N and C uptake were significant at the lowest P rate. P increases promoted growth and total shoot nutrient contents in low N-treated seedlings, while reducing growth in higher N rates. The combined application of medium and high rates of N and P fertilizers showed relatively low impact on seedling growth presumably because of suboptimal N:P ratios. Mycorrhizal root colonization was generally low (≤ 12%) and was not affected by any of the treatments. There was also no response to inoculation with AM fungi probably because the established mycorrhizal association was ineffective. The potential use of both mineral fertilizers and AM fungi to promote growth performance of shea seedlings are discussed.