Thesis (M. Sc. (Agricultural Management)) -- University of LImpopo, 2002 / Refer to document / NRF (National Research Foundation) and WRC (Water Research Commission)

Efficacious timing and rate of synthetic fertilizer nitrogen (N) application can reduce the amount of N needed to be applied for potato production. The purpose of this study was to compare combinations of source, timing, and application methods of different synthetic N fertilizers on yield and quality of irrigated Russet Burbank, processing potato in Manitoba. Source, timing, and application method combinations were examined to provide a range of N availability over the growing season. This study was conducted at two sites over two years. Split applications of granular urea or Super-U, addition of ESN at planting and split application of granular urea at planting and fertigation were the most consistent treatments for highest marketable yield and nitrogen use efficiency. ESN was advantageous in wet site conditions. The results indicate split application of granular urea and split granular urea and fertigation that growers of processing irrigated potato primarily use in Manitoba are sound management practices. / February 2016

The influence of agronomic practices on forage production and chemical composition of grass-legume pasture mixture was studied at the Utah State University Dairy Farm, North Logan, Utah, during spring and summer, 1970. The soil is a well-drained Millville silt loam that has about a 1 percent slope . It is high in potash, phosphorus, and lime, having a pH of 7.9. Analysis of the clipping management showed that the early spring clipping decreased the yield of forage. The losses in total yield due to spring clipping were approximately four to five times the yields received in early spring clipping. The grasses were affected more than the legumes. The yields of dry forage increased with the increase in fertilizer rates from 0 through 300 pounds of nitrogen per acre. There was no advantage to splitting the nitrogen fertilizer of 300 pounds per acre into three applications. Most of the effects of spring clipp1ng and nitrogen fertilization were re fleeted in the first summer harvest. The plots fertilized with nitrogen produced a higher yield and nitrate content than the check plots. Legumes were higher in nitrate on the unfertilized plots than the grasses, but lower on the fertilized plots.

Cotton (Gossypium hirsutum L.) and corn (Zea mays L.) spectral reflectance holds promise for deriving variable rate N (VRN) treatments calibrated with red-edge inflection (REI) type vegetation indices (VIs). The objectives of this study were to define the relationships between two commercially available sensors and the suitable VIs used to predict N status. Field trials were conducted during the 2012-2013 growing seasons using fixed and variable N rates in cotton ranging from 33.6-134.4 kg N ha-1 and fixed N rates in corn ranging from 0.0 to 268.8 kg N ha-1. Leaf N concentration, SPAD chlorophyll and crop yield were analyzed for their relation to fertilizer N treatment. Sensor effects were significant and red-edge VIs most strongly correlated to N status. A theoretical ENDVI index was derived from the research dataset as an improvement and alternative to the Guyot’s Red Edge Inflection and Simplified Canopy Chlorophyll Content Index (SI).

Durum grain quality is affected by many factors, but water and nitrogen are factors that the grower can control. The purpose of this research was to determine 1) the nitrogen application rate required at pollen shed to maintain adequate grain protein levels if irrigation is excessive or deficient during grain fill and 2) if nitrogen applications during grain fill can elevate grain protein. Field research was conducted at the Maricopa Agricultural Center using the durum varieties Duraking, Minos, and Turbo. The field was treated uniformly until pollen shed when nitrogen was applied at rates of 0, 30, and 60 lbs/acre. During grain fill, the plots were irrigated based on 30, 50, or 70% moisture depletion. In a separate experiment, nitrogen fertilizer was applied at a rate of 30 lbs N/acre at pollen shed only, pollen shed and the first irrigation after pollen shed, and pollen shed and the first and second irrigation after pollen shed. Irrigation had no effect on grain protein level, although increasing nitrogen rates at pollen shed from 0 to 30 and 30 to 60 lbs N/acre increased protein by 1 percentage point. Nitrogen fertilizer application at the first irrigation after pollen shed increased grain protein content from 10.4 to 11.4% and application at the first and second irrigation after pollen shed increased grain protein content further to 11.9% averaged over varieties. Irrigation management during grain fill may not play as large a role in controlling grain protein content as was originally thought except perhaps on heavy soils, and nitrogen fertilizer application during grain fill may not be too late to increase grain protein content.

No description available.

Application of nitrogen (N) fertilizer in conjunction with the irrigation event occurring closest to the flowering stage is effective in reducing the incidence of yellowberry and boosting grain protein levels of durum wheat. However, N applications at this time normally do not increase grain yield, except perhaps on very sandy soils. A field experiment was conducted to determine the profitability of applying 35 pounds of N per acre at flowering to durum wheat to avoid dockage for poor grain quality. Two treatments consisted of a check plot with no N applied at flowering and UAN 32 water run at a rate of 35 lbs. N /acre to basin irrigated durum wheat grown on a loamy sand soil. Maximum durum wheat grain yield (6157 lbs. /acre), protein concentration (13.7 %), and corrected income per acre ($480.31) was obtained with the N fertilizer application. In fact, N fertilization at flowering on this sandy soil increased durum wheat grain yield by 255 lbs. /acre compared to the unfertilized plot.

No description available.

Master of Science / Department of Agronomy / Charles W. Rice / Agricultural lands receiving N inputs are considered the primary source of N2O, a potent greenhouse gas. N fertilizer management has shown variable effects on both N2O losses and corn grain yield. The objectives of this study were to assess the impact of N source and placement on N2O emissions, fertilizer-induced emission factor (FIEF), corn grain yield, yield-scaled N2O emissions (YSNE) and N fertilizer recovery efficiency (NFRE). The experiment was conducted from 2013 through 2014 at the Agronomy North Farm located at Kansas State University, Manhattan, KS. The soil was a moderately well-drained Kennebec silt loam. The treatments were broadcast urea (BC-Urea), broadcast urea ammonium nitrate (UAN) (BC-UAN), broadcast coated urea (BC-CU), surface-band UAN (SB-UAN), subsurface-band UAN (SSB-UAN), subsurface-band UAN + nitrification inhibitor (SSB-UAN+I) and a 0 N control. In 2013, SSB- UAN emitted significantly more N2O (2.4 kg N2O-N ha-1), whereas control (0.3 kg ha-1) and BC- UAN (0.6 kg ha-1) emitted the least. In 2014, most treatments emitted between 3.3 and 2.5 kg N2O-N ha-1. Only SSB-UAN+I (1.03 kg ha-1) and control (0.26 kg ha-1) were significantly lower. The use of a nitrification inhibitor decreased N2O emissions by 62% and 55% in 2013 and 2014, respectively. BC treatments had cumulative emissions significantly higher in 2014 compared to 2013. Only SSB-UAN+I had a significantly lower FIEF (0.4%), and 2013 FIEF (0.68%) was significantly lower than that of 2014 (1.38%). In 2013, banded treatments had significantly higher grain yields (from 9.1 to 10.5 Mg ha-1), whereas in 2014 fewer differences among N treatments were observed, ranging from 7.2 to 8.6 Mg ha-1. Banded treatments had significantly lower grain yields in 2014 compared to 2013. Only BC-UAN and SSB-UAN+I had significantly lower YSNE, and 2013 had lower YSNE than 2014. In 2013, SSB-UAN had the greatest NFRE, whereas BC treatments had the lowest. In 2014, N treatments did not differ in NFRE. SSB-UAN and SSB-UAN+I had significantly lower NFRE values in 2014 compared to 2013. Fertilizer source and placement have the potential to mitigate N2O emissions and promote high yields and NFRE in corn, however, the response is dependent on the rainfall pattern after fertilizer application. The option of banding UAN without any additive promoted higher N2O losses on a year when precipitation was well distributed, but also enhanced grain yield and NFRE. On the other hand, under the same precipitation conditions, broadcasting N fertilizer promoted lower N2O losses, grain yield and NFRE, but those were all improved in a wet year. Therefore, the subsurface band placement would be the best option under a normal year, whereas broadcasting fertilizer would be the best option under a wetter year. Further, the use of NI with subsurface band UAN provides the most sustainable option, since the NI decreased N2O losses compared to UAN alone in both years. Further research should evaluate N source and placement combinations under different environments in order to better understand how they impact crop performance and the negative environmental aspects of N fertilization. It is important to test those treatments under different precipitation scenarios and look for trends that indicate the best N management option at the local level.

2007 metais ūkininkų E. Guževičiaus (Alytaus r.) ir V. Svoto (Vilkaviškio r.) ūkiuose atlikti gamybiniai lauko bandymai. Vilaviškio rajono dirvožemiai yra vidutiniškai humusingi ir humusingi, turintys didelį magnio ir mažą mineralinio azoto kiekį. Judriojo fosforo ir kalio čia esti vidutiniškai. Šie dirvožemiai priskiriami prie išplautžemių. Alytaus rajone vyrauja lengvo priemolio karbonatingi išplautžemiai ir karbonatingi giliau glėjiški rudžemiai, kuriuose gausu magnio, kiek mažiau kalio, vidutiniškai – humuso ir mineralinio azoto. Tyrimams pasirinkti skirtingų rajonų ūkiai su skirtingomis dirvožemio ir agroklimatinėmis sąlygomis, siekiant įvertinti skystųjų azoto trąšų su aminorūgštimis įtaką žieminių kviečių ir vasarinių miežių derliui ir derliaus kokybei. Nustatyta, kad skystosios amidinio azoto trąšos su aminorūgštimis nežymiai didino žieminių kviečių produktyvumo elementus, tačiau skirtingų koncentracijų poveikis buvo kitoks. Karbonatiniame išplautžemyje gausiausias grūdų derlius gautas miežius patręšus trąšomis su 1,5% aminorūgščių. Kituose laukeliuose gauti derliaus pokyčiai buvo neesminiai. Aminorūgštys įtakojo žaliųjų proteinų kaupimąsi grūduose. Nustatyta, kad skystosios amidinio azoto trąšos su aminorūgštimis didino žieminių kviečių grūduose baltymų kiekį, sedimentacijos ir šlapiojo gilitimo vertes. / In 2007, farm production field trials were carried out in the E. Guževičius (Alytus region) and V. Svotas (Vilkaviškis region) farms. In Vilkaviškis region the soils are average humous and humous, with high level of magnesium and low level of mineral nitrogen. The mobile phosphorus and potassium is found in the average quantities there. These soils belong to scour soil. In Alytus region light loam carbonative scour soil and carbonative deeper slimy brown soils predominate. These brown soils are rich in magnesium, potassium to a lesser extent, on average - humus, and mineral nitrogen. The farms from different regions not only with different soils, but even with variant agro-climate conditions were selected for the research, to evaluate the liquid nitrogen fertilizer with amino acids influence on winter wheat and spring barley harvest and crop quality and technological properties. Found that liquid amidive nitrogen fertilizer with amino acids slightly increased the productivity of winter wheat cells, but the effects of different concentrations were totally mixed. In the carbonative scour soil the largest grain yield was obtained when barley was feeded fertilizers with 1.5% amino acids. Other options to receive the crop change was minor. Amino acids affected the crude protein and fat accumulation in grain. Found that fertilization liquid amidive nitrogen fertilizer with amino acids increased the grain protein content, sedimentation, and wet gluten values.