The purpose with this report was to compare three commonly occurring methods for measuring plant available nitrogen in soils. The methods extraction, incubation and Plant root simulator (PRS) probe - an ion exchange membrane (Western Ag Innovations, Inc., Saskatoon, Canada) method were used and comparison between these methods were conducted. A full factorial experiment were set up in northern Finland with the treatments excluding herbivores, warming and fertilization to see how the inorganic nitrogen content in the soil was effected by the treatments. Soil cores were taken and from them a subsample was incubated for 18 days and thereafter analyzed for inorganic N in laboratory. PRS- probes were in the ground for 1 month. It was a strong positive correlation between extracted and incubated samples but no correlation between the PRS- probes and extraction or incubation samples. The PRS- probes showed several significant changes in inorganic N content after the treatments where fertilization increased the tot-N and NO3 levels and warming reduced the inorganic tot-N, NH4 and NO3. These findings were not confirmed by the results of the extraction. The incubation showed negative net mineralization rates for tot- N and NH4. PRS- probes showed a slightly dominance of NO3 over NH4 while extraction showed a many times higher amount of NH4 compared to NO3. Extraction shows a strong correlation with incubation even though extraction measure an instantaneous value and incubation measure the production of inorganic nitrogen over time.

8 pp. / Reviewed 2/2017; Originally Published 2000 / El manejo apropiado del riego requiere la evaluación de parte del agricultor de sus necesidades de riego en base a medidas de varios parámetros físicos del suelo. Algunos productores utilizan equipo sofisticado mientras que otros se basan en métodos empíricos o en el sentido común. Cualquiera que sea el método usado, cada uno tiene sus propios méritos y limitaciones. El agricultor generalmente se hace dos preguntas al desarrollar una estrategia para el manejo del riego: “¿Cuándo regar?” y “¿Cuánta agua aplicar?”. Este boletín responde a la pregunta CUÁNDO. Reviewed 2/2017; Originally Published 09/2010.

Urban soils are typically degraded due to land disturbance. The poor quality physical and chemical properties of the soil can benefit from application of organic amendments. Local sources of such amendments are biosolids, which are treated domestic wastewater sludges. The objective of this experiment was to compare effects of various high quality biosolids-based soil amendments with synthetic fertilizer on the growth and quality of tall fescue (Schedonorus arundinaceus) under two different soil moisture regimes. The research site was a disturbed soil at the Virginia Tech Turfgrass Research Center in Blacksburg, Virginia. The experimental design was a split plot with irrigation regime as the main factor and soil amendments as the split factor. All treatments were arranged in four randomized complete blocks. The study was established in late summer 2013. Soil amendment treatments, applied prior to seeding in September 2013, were: 1) inorganic N, P, K applied according to soil test laboratory recommendations; 2) anaerobically digested, dewatered biosolids to supply agronomic N rate; 3) anaerobically digested, dewatered biosolids blended with sand and sawdust to supply agronomic N rate; 4) anaerobically digested, dewatered biosolids blended with sand and sawdust to supply agronomic P rate; and 5) composted biosolids to supply agronomic N rate. The agronomic N rate for the turfgrass was 224 kg of estimated plant available nitrogen (PAN) ha-1. Inorganic fertilizer was applied to supply annual P and K requirements prior to seeding in late summer, and the N was split into three application timings (September 2013, April 2014, and June 2014). Supplemental fertilizer N to achieve full agronomic N rate was applied to the treatment plots that received the agronomic P rate of blended biosolids-sand-sawdust. The area was seeded on September 13, 2013 with a tall fescue blend at a rate of 488 kg ha-1. Following full tall fescue establishment, in June 2014, two irrigation regimes, consisting of 0% and 80% evapotranspiration replacement every three days, were initiated. The study had three phases denoted as the pre-drought, drought, and recovery phases which started in April and concluded in August of 2014. Turfgrass color and quality, volumetric soil moisture percentage to a 5 cm depth, normalized difference vegetative index (NDVI), clipping yield, and turfgrass N uptake were measured bi-weekly throughout the growing season. During the first May through July 2014 irrigation season, results were that the fertilizer control consistently provided improved responses relative to the biosolids amended treatments. Clipping yield, quality, and NDVI were all significantly greater in the inorganic fertilizer treatment, but volumetric soil moisture percentages were slightly greater in the biosolids treatments. Turfgrass responses appeared to have been associated with plant available nitrogen, which was lower in the biosolids treatments than in the fertilizer treatment. Calculated PAN for the biosolids products was too low to achieve ideal turfgrass growth and quality. Improving the estimated PAN and/or splitting the organic amendment application times should improve the growth and quality of the turfgrass. / Master of Science

Abstract Salinity has considerable adverse effects on agriculture through reduction in plant growth and water use. Sodium chloride salinity has both an osmotic effect on plant water relations, and a toxic effect on cellular processes. The relative contribution of these two effects to plant growth depends on a range of factors including plant specific tolerance mechanisms, such as Na and Cl exclusion, compartmentation of ions at a whole plant and cellular level, and synthesis of organic osmotic compounds for plant osmotic adjustment. Plants growing in saline soil would also experience reduced plant available water, due to the additional osmotic effect on soil water potential. The effect of salinity on plant growth is further complicated by the interactions of environmental conditions with plant water and ion uptake. This thesis examines the osmotic and toxic effects of salinity on wheat (Triticum aestivum L.) and chickpea (Cicer arietinum L.), with particular focus on plant water availability, effects of Na and Cl toxicity, and temperature and humidity effects. While considerable research has been undertaken into the physiological response of plants to NaCl, our understanding of the capacity of plants to extract water from saline soils has remained largely theoretical. Total plant available water is largely determined by the matric potential of the soil. Presence of sodium chloride would have an additional osmotic effect, and previous theory stated that the salt tolerance of the plant determined the extent to which this osmotic potential reduced plant available water. The capacity of wheat and chickpea to extract water from saline soils was examined in a soil experiment where water stress was imposed on established plants, which were then grown until permanent wilting point (PWP) was reached. Wheat extracted to lower soil water potentials (-1.5 MPa), than chickpea (-900 kPa) in 0 NaCl treatments. Where salinity was low to moderate, plants were able to extract water to a PWP determined by the combined total of matric and osmotic potentials. Wheat extracted water to PWP in salinity treatments up to soil ECse of 5.3 dS/m, and chickpea to 2.9 dS/m. As salinity increased, toxic effects of salinity dominated, and water extraction by plants was significantly lower than that determined by total soil water potential. Solution culture experiments investigated the comparative toxic effects of Na, Cl and salt mixtures. Growth of wheat was reduced by Na toxicity, but not Cl toxicity, with Na causing a small, but significant additional reduction in growth, compared to high Cl or a salt mixture. Reductions in growth of 50% from control treatments occurred at -500 kPa for the Na treatment, and -630 kPa for the Cl and mixed salt treatments. In contrast, growth of chickpea was significantly reduced by both Na and Cl toxicity, with a large difference in growth compared to the salt mixture. Growth reductions of 50% occurred at -330 kPa for the Cl treatments, and -450 kPa for the Na treatment. A 50% growth reduction was not observed in the mixed salt treatment. Tolerance of saline conditions is reduced under stressful environmental conditions, such as high temperature and low relative humidity. Hot and dry conditions were shown to reduce the tolerance of saline conditions by both wheat and chickpea, compared to cool or humid conditions. Tissue concentrations of Na in wheat were disproportionately high in treatments with high evaporative demand, while tissue Cl was not related to evaporative demand. Tissue concentrations of Na in chickpea increased with temperature, but not relative humidity, while tissue Cl concentrations were highly correlated with evaporative demand. The relationships between NaCl salinity, plant water use, and environmental conditions were examined, allowing further development of the two phase salinity model. In particular, the transition point between the osmotic and toxic salinity effects. While the concentration of NaCl in the soil remains the primary factor, soil water status, environmental stresses and presence of other salts may dictate whether salinity be tolerated by the plant or not. The ability of the plant to extract water to PWP, as determined by total matric and osmotic potential has been identified as a useful indicator of salinity tolerance. The point at which toxicity of Na and/or Cl is observed is associated with a rapid increase in Na and Cl uptake by the shoot tissue, and a decrease in the amount of water the plant is able to extract from the soil. Within the osmotic region of salinity stress, the plant is able to extract water to PWP, but as NaCl becomes toxic the plant is unable to utilize this water.

Commonly used soil analysis and resin capsule procedures are used to assess nutrient status in fertile soils, but their validity in semi-arid ecosystems is unknown. Three studies were performed to assess resin capsule effectiveness in semi-arid ecosystems. An incubation study was completed in which loamy sand and sandy clay loam soils were treated with rates of N, P, Fe and Zn. Each soil treatment was implanted with a resin capsule and incubated for 60 or 120 days. Resin capsules reflected NH4-N and P fertilizer at low rates in the loamy sand. NO3-N reflected rates in both soils, but did not reflect Fe or Zn application. Resin capsule NH4-N was a better indicator than KCl-extractable NH4-N, but resin capsule NO3-N was not as effective as water extraction, and resin capsule P was poor compared to NaHCO3-P. A second study was performed in glasshouse conditions using the incubation study soils. Soils were treated with rates of N, P and resin capsules were placed in pots. Pots were seeded with squirreltail grass (Elymus elymoides) and placed in a glasshouse. Resin capsules were removed at 120 days, soil samples taken, grass harvested and yield measured. Yield and total nutrient removal was correlated to resin NH4-N, marginally related to resin or soil NO3-N, and unrelated to resin P. Yield and total nutrient removal was correlated with application rates and resin NH4-N and NaHCO3-extracted P. The third field study, compared two sites with rates of N and P application were established on clay loam and sandy loam soils. Resin capsule and conventional soil tests for NO3-N, NH4-N and P were measured and plant nutrient status examined. Resin capsules were removed and replaced and soil samples taken every 90 days. Resins P was not related to P application or to plant tissue P but NaHCO3-extracted P was, while resin NO3-N, KCl-extracted NO3-N and NH4-N were correlated to N application and plant N. Soil test P was more effective in predicting P status and bioavailability than resin capsules. Resin NH4-N and NO3-N predicted N status and bioavailability, but soil tests were just as effective in semi-arid conditions.

Ion exchange resin capsules provide a possible alternative to conventional soil testing procedures. Previous studies with semi-arid, low fertility soils observed poor relationships with poorly mobile nutrients such as phosphorus (P). We propose that placement depth may improve those relationships. Our objective was to (1) determine if placement depth could improve resin capsule estimation of the bioavailability of nitrogen (N), P, and sulfur (S) and (2) to determine if resin capsules can effectively estimate S availability in semi-arid, low fertility soils. Field sites were established in Rush and Skull Valleys, Utah on loam and sandy loam soils, respectively. Fertilizer was surface applied as ammonium sulfate and triple superphosphate with six N, P and S treatments (0, 5.5, 11, 22, 44 and 88 kg ha-1 of N and P2O5 and 0, 7, 14, 28, 56 and 112 kg ha-1 of S). Thirty 4.0-m2 plots were established at each field location. Resin capsules were placed three per plot at 0–5, 5–10, and 10–15 cm deep in the soil and soil samples taken at respective depths. The capsules were removed and replaced after approximately 90 d. Final removal and soil sampling occurred approximately 240 d later. For the second study, fertilizer was surface applied as ammonium sulfate with six S treatments (0, 7, 14, 28, 56 and 112 kg ha-1 of S) with one resin capsule placed in each 4.0-m2 plot at a depth of 5 cm in the soil. Resin capsules were removed and replaced approximately every 90 d for a total of four samplings. Soil samples were taken with every resin capsules install and removal. In the first study, bicarbonate extractable P was significantly related to P application at all depths and times except the two lowest depths at the time of final sampling, and resin capsule P was only related to P application 398 days after application in the 0–5 and 5–10 cm depths. However, this is an improvement in estimates of bioavailability compared to a single placement depth. The 5–10 cm depth was the best for placement for determination of NH4-N, and resin capsules improved upon soil test estimates. For NO3-N, depth was not important, but resin capsules had a stronger relationship with N applied than the soil test 398 d after application. In addition, both resin capsules and the S soil test were related to S applied, but resin capsules were more able to pick up S cycling through the system. In the second study resin capsules and conventional soil tests were both effective in distinguishing between fertilizer rates, though only the conventional soil test was related to S applied at the last sampling (366 d after fertilizer application). Overall resin capsules were effective at reflecting application rates, and may be a good tool to estimate nutrient bioavailability. Correlation with plant uptake is required to determine if soil tests or resin capsules were a better estimate of bioavailable nutrients.

Composted biosolids have been shown to enhance turfgrass establishment and growth more than fertilizer alone, but few studies have investigated the production of turfgrass using uncomposted biosolids. Increasingly employed treatment methods that generate pathogen-free, low pollutant-containing biosolids are creating alternative products for use in urban settings.  Understanding the effects of these uncomposted and alternative biosolids products on turfgrass culture and soil chemical and physical properties is essential to understanding the benefits these products may provide in sod production systems. The objectives of this study were to compare processing methods, application and N mineralization rates of two biosolids products and an inorganic fertilizer control for sod fertilization on 1) agronomic parameters related to turfgrass quality, 2) the amount of soil, C and P exported at harvest, and 3) chemical and physical properties of the soil following sod harvest as an indicator of the benefits of biosolids use. The study was conducted on a sod farm in Remington, Virginia on a silt loam Ashburn-Dulles complex from 2009 to 2012. The biosolids products were applied at estimated plant available nitrogen (PAN) rates of 98 kg N ha-1  (0.5X), 196 kg N ha-1 (1.0X) and 294 kg N ha-1  (1.5X) for a tall fescue (Festuca arundinacea Schreb. \'Rebel Exeda\' \'Rebel IV\' and \'Justice\')/ Kentucky bluegrass (Poa pratensis L. \'Midnight\') mixture. One biosolids product was an anaerobically digested dewatered cake applied at 15, 30.5 and 46 wet Mg ha-1. The second biosolids product was the same cake blended with wood fines applied at 17, 34 and 51 wet Mg ha-1. The biosolids treatments were compared to an inorganic fertilizer control that supplied 196 kg N ha-1 through three applications over the production cycle. There were no differences in establishment between the cake biosolids treatments and the inorganic fertilizer control, but all of the blended biosolids were slower to establish. Only the 1.0X and 1.5X PAN rates from the cake biosolids matched the inorganic fertilizer control in producing an acceptable quality sod in ten months. Lower nitrogen uptake between the blended biosolids treatments compared to the inorganic fertilizer control and lower although acceptable sod quality ratings at harvest of the 1.0X cake biosolids indicate our PAN estimates of 30% organic nitrogen mineralization overestimated the PAN for both materials. There were no differences in sod tensile strength between the 1.5X cake biosolids and inorganic fertilizer control. There were no differences in transplant rooting strength among all treatments. After repeat applications of biosolids, the 0.5X rates did not increase soil extractable phosphorus, while the 1.0X rates steadily increased soil extractable phosphorus at. The 1.0X and 1.5X biosolids rates increased soil organic matter content, but only the 1.5X rate of cake biosolids reduced soil bulk density and mineral matter export at harvest. Overall results indicate that the cake biosolids are an acceptable fertility alternative to inorganic fertilizer, and applications of biosolids for sod production can improve soil quality. Sod growers should consider using biosolids in a rotational system to offset rising production costs and improve production field soil quality. / Master of Science

To achieve a sustainable use of energy we must increase our use of renewable energysources, biogas if one such source. One of the greatest potentials for biogas are in theagricultural sector and the Energy Agency calculates that 25% of the available manurecan be used for biogas production. The purpose of this thesis is to contribute withknowledge of co-digestion of manure and how this affects the methane potential andhow co-digestion affects the contents of NH4 in the sludge. The report includes a literature study to understand the digestion process and its partsand allows interpretation of data. The report includes analysis of data from HalmstadUniversitys experiment of anaerobic digestion and an additional digestion. The resultsobtained in this study shows that the effect of co-digestion varies depending on manure.Horse and chicken manure and beef and pig manure gives a positive effect to the codigestion.

In den meisten Ländern Mitteleuropas gilt weniger als ein Prozent des verbleibenden Laubwaldes als ungestört und temperierte Wälder sind Herausforderungen wie Arteninvasion, Klimawandel und steigender Stickstoff(N)-Deposition ausgesetzt. In der Vergangenheit wurde gezeigt, dass hohe N-Einträge N-Limitierungen verringern, Phosphor(P)aufnahme behindern und P-Mängel in der Buche auslösen können. Die Artendiversität von Bäumen kann die Bestandsproduktivität durch die Prozesse Komplementarität und Facilitation (Wachstumserleichterung) erhöhen, wenn diese einen wachstumslimitierenden Nährstoff betreffen. Ein Schlüsselprozess im Nährstoffkreislauf ist der Weg von Nährstoffen durch die mikrobielle Biomasse während der Dekomposition. Es wurde gezeigt, dass die mikrobielle Biomasse um N bspw. mit Buchen und um P mit tropischen Moorpflanzen konkurriert. Die Buche ist eine sehr konkurrenzfähige Baumart in temperierten Waldökosystemen aber kann von der Eiche in trockenen Bereichen übertrumpft werden, während Hainbuche und Linde eine geringere Rolle spielen. Eichen erfahren jedoch in der jüngsten Vergangenheit in europäischen Wäldern einen Rückgang, der womöglich auf hohe N-Einträge zurückzuführen ist. Für diese Arbeit untersuchten wir die Nährstoff-, Konkurrenz- und strukturelle Dynamik eines unbewirtschafteten, sehr naturnahen Laubwaldes in Mitteldeutschland, der aus Buche (Fagus sylvatica), Eiche (Quercus petraea und Quercus robur), Hainbuche (Carpinus betulus) und Linde (Tilia cordata und Tilia platyphyllus) aufgebaut ist. Unsere Ziele waren (1) zu erforschen, ob Komplementarität und/oder Facilitation die Produktivität in diesem Waldökosystem erhöht, (2) festzustellen, ob es Konkurrenz um die Nährstoffe N, P und K zwischen Bäumen und mikrobieller Biomasse gibt und, (3) die Nachbarschaftsdynamik der genannten Baumarten zu untersuchen und herauszufinden, ob der Eichenrückgang mit hoher N-Deposition einhergeht. In Beständen einer Art sowie verschiedenen Mischbeständen aus je drei Arten ermittelten wir Biomasseproduktion und Nährstoffverfügbarkeit. Nährstoffnutzungseffizienzkurven (Nährstoffnutzungseffizienz = Biomasseproduktion pro verfügbare Nährstoffe) wurden genutzt um festzustellen, ob ein bestimmter Nährstoff das Baumwachstum limitiert. Die jährliche Netto-Nährstoffveränderung wurde in einer Laubbeutel-Studie als Differenz zwischen ursprünglichem und verbleibendem Nährstoffgehalt des sich zersetzenden Laubfalls nach einem Jahr kalkuliert. Die Nährstoffresorptionseffizienz berechneten wir über die Ermittlung der N-, P- und Kalium(K)-Konzentrationen in sonnenexponierten Blättern und im gefallenen Laub. Die Nachbarschaftsdynamik von Bäumen wurde über die Durchmesserverteilung, überirdische Holzbiomasse für jede Artenkombination sowie eine Polygon-Abschätzung von Wachstumsräumen erforscht. Zusätzlich wurde eine durchmesserbasierte nearest neighbor(nächster-Nachbar)-Analyse für Baumpaare durchgeführt. Ein Geographisches Informationssystem (GIS) wurde genutzt um Wachstumsraum-Polygone zu erstellen und nächste Nachbarn zu bestimmen. Auf Einzelbaum-Level, ermittelt durch einen Nachbarschaftsansatz, waren relative Wachstumsraten von Buchen im Einzelbestand geringer als in der Mischung mit Linde und Hainbuche während das Wachstum von Linde im Einzelbestand größer war als in Mischung mit Buche und Eiche. Die Nährstoffnutzungseffizienzkurve für Buche zeigte optimale P- und K-Nutzungseffizienz für die Art in Mischbeständen, während sie in Einzelbeständen  P- und K-limitiert war. Während die jährliche Netto-Nährstoffveränderung in sich zersetzendem Blattlaub die Verfügbarkeit von P und K im Boden beeinflusste, war dies für N nicht der Fall. Resorptionseffizienzen von N, P und K hingen negativ mit der jährlichen Netto-Nährstoffveränderung zusammen. In unserer Studie zur Nachbarschaftsdynamik von Bäumen fanden wir heraus, dass intraspezifische nearest neighbors gleiche Durchmesser aufwiesen und ihren Durchmesser gleichzeitig mit dem des Nachbarn vergrößerten. Im Gegensatz dazu waren die Durchmesser von interspezifischen nearest neighbors im Allgemeinen unterschiedlich und der Durchmesser des Nachbarn verringerte sich mit zunehmendem Durchmesser des Zielbaums. Eichen konnten ihren Wachstumsraum mit zunehmendem Durchmesser nicht vergrößern, aber dominierten ihre nearest neighbor über die Größe. Unsere Ergebnisse zeigten, dass im untersuchten Waldökosystem Nährstofflimitierungen artabhängig waren und dass die Nutzung von Nährstoffnutzungseffizienz und Nachbarschaftsansatz geeignete Mittel sind, den Einfluss einzelner Baumarten auf die Produktivität einer Art im Rein- und Mischbestand zu ermitteln – so wie die beobachtete Facilitation der Buche im Mischbestand. Diese Werkzeuge stellen eine wichtige Basis zur verbesserten Bewirtschaftung typischer temperierter Mischwälder dar. Wir schlussfolgerten weiterhin, dass Konkurrenz zwischen mikrobieller Biomasse und Bäumen für P und K hoch, aber für N weniger bedeutend war, was wahrscheinlich in hoher N-Deposition in diesem Waldökosystem begründet liegt, welche den internen N-Kreislauf entkoppelte. Die hohe N-Deposition trug wahrscheinlich auch zu geringer Verjüngung der Eiche bei, während ältere Eichen in unserem Untersuchungsgebiet im Wettbewerb um Licht erfolgreich waren. Die Bestandsstruktur war charakterisiert durch stärkere interspezifische verglichen mit intraspezifischer Konkurrenz. Daraus resultierend bildeten Reinbestände aus Buche, Eiche und Linde Klimaxbestände hoher Biomasse innerhalb eines sich verändernden, kleinskaligen Mosaiks verschiedener Artenzusammensetzungen. In Reaktion auf neue Bewirtschaftungsanforderungen des Globalen Wandels sind weiterführende Forschungen zu Nutzungseffizienz unterschiedlicher Ressourcen für Baumarten in verschiedenen Zusammensetzungen empfehlenswert.

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