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Item The effects of the application of large amounts of nitrogen fertilizer on milk yield, reproductive performance, and energy balance of spring-calved high genetic merit cows : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Sciences in Animal Production at Massey University, Palmerston North, New Zealand(Massey University, 2005) Ordóñez, AlfredoThe intake of crude protein (CP) in amounts considerably above the cow's requirements has been associated by several overseas (OS) reports with reduced cow performance. In New Zealand (NZ), the CP content of pasture during spring is usually above the cow's requirements. During this time, application of nitrogen (N) fertilizer is a common practice which further increases the CP content of pasture. Despite this fact, few experiments have studied the effect of high CP intake on cow performance in NZ, and the existing results are not conclusive. Therefore, the objective of this experiment was to measure the effect of two levels of CP concentration in pasture caused by application of different amounts of N fertilizer, on milk yield, reproductive performance, and energy balance of grazing, spring-calved, high genetic merit cows in NZ. Two groups, each of 20 high genetic merit cows, were offered a common pasture allowance (46 kg OM/cow/day) over the first 101 days postcalving, but from pasture which contained either a lower (low CP group) or a higher concentration (high CP group) of crude protein. The difference in CP concentration was created by applying either no N fertilizer or 35 kg of N fertilizer after every grazing. Herbage masses were measured on every paddock weekly, and every day pregrazing and postgrazing, using a rising plate meter. These values were used to calculate pasture growth, and apparent dry matter intake per group. Pasture composition was measured by near infrared spectroscopy. For each cow, milk yield and composition was measured by weekly herd tests. Reproductive performance was assessed by scanning of follicles and corpora luteal from day one until day 40 postcalving, and from 10 days before the predicted artificial insemination (Al) until 35 days post Al. Progesterone concentrations were measured in milk samples taken every second day. Liveweight and condition score of each cow were measured weekly, and concentrations of NEFA and IGF1 were measured in blood samples taken II once every week. Energy balance was calculated as theoretical energy requirements minus estimated energy intake, and feed conversion efficiency was also calculated. When compared with the low CP paddocks, the high CP paddocks produced more pasture (+1,260 kg OM/ha in 101 days) and it was of higher quality (11.8 vs. 11.4 MJ ME/kg OM; 83.4% vs. 81.2% digestibility; 24.5 vs. 21.6% CP). The apparent daily intakes of OM and ME of the two groups were not significantly different (16.2 and 15.9 kg OM/cow; 195 and 184 MJ ME/ cow). However, the high CP group ate significantly more CP than the low CP group (4.2 vs. 3.5 kg CP/cow/day, and had a higher blood urea concentration (7.8 vs. 5.3 mmol/I). There were no significant or consistent differences between the two groups in milksolids yield (1.84 vs. 1.91 kg MS/cow/day for the high and low CP groups), reproductive measurements, liveweight, condition score or IGF1 concentrations. However, the high CP group had significantly lower NEFA concentrations than the low CP group (0.45 vs. 0.56 mmol/I). The high CP group had lower apparent feed conversion efficiency than the low CP group, which may have been partially due to the calculated value of 3.2 MJ ME extra required per day to excrete the extra urea from the high CP group. In conclusion, even though the high CP group had higher blood urea concentrations, no significant differences in cow performance were detected between the two groups. The application of 130 kg N/ha produced an extra 1,264 kg OM/ha, which would have been expected to produce an extra 140 kg MS/ha, although this increase in MS yield may have been reduced slightly (by 9%) by the lower calculated feed conversion efficiency of the high CP group. Subject for further research include attempts to increase the feed conversion efficiency of animals grazing pastures with high CP content, through the use of sources of extra rumen degradable energy; the effect of diets high in CP on embryo quality and viability; and the ecological impact of using large amounts of N fertilizers.Item Soil nitrogen studies with particular reference to fruit-tree nutrition : being a thesis submitted in partial fulfilment of the requirements for the degree of Master of Agricultural Science (Hort.) of the University of New Zealand(Massey University, 1952) May, E.B.The importance of nitrogen for the nutrition of fruit trees is well established and it is largely for this reason that much attention has been given by overseas workers to factors influencing the level of soil mineral nitrogen. Soil managment methods have been shown to exert a considerable infleunce on mineral nitrogen level of the soil, those methods which make nitrogen available most readily depleting the total supply in the soil most rapidly. In view of the importance attached by overseas workers to the influence of soil managment practices on the level of the soil mineral nitrogen, and as no previous study of this problem appeared to have made in New Zealand, the present investigation was undertaken. A study was made to compare the effects of clean-cultivation and sod-culture on both the mineral level and pH in a silt-loam orchard soil over a period of several months. This afforded an opportunity to investigate also the effect of seasonal factors on the periodic variations in mineral nitrogen under both systems of management. [From Introduction]Item Effect of nitrogen fertilizer placement on nitrogen uptake and yield of sweet corn (Zea mays L. saccharata) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Plant Science at Massey University, New Zealand(Massey University, 1986) Wongpichet, KittiFive placements of nitrogen fertilizer applied to sweet corn (Zea mays L. saccharata) at the four fully expanded leaf stage, that is control (no nitrogen), a band of nitrogen placed on the soil surface near the row, on the soil surface between the rows, at 3 cm depth between the rows and at 10 cm depth between the rows were studied following three sowing times. Total plant nitrogen and sap nitrate were determined along with total plant dry weight at six growth stages. Leaf extension and leaf appearance were also followed in order to monitor the response of plants to nitrogen fertilizer applied. Nitrogen fertilizer application resulted in significantly higher nitrogen uptake, plant dry weight and marketable ears under both dry and wet conditions. Nitrogen fertilizer applied at 10 cm depth between rows resulted in significantly higher nitrogen uptake, plant dry weight and marketable ears than that applied on the soil surface between rows under dry condition. Nitrogen fertilizer applied on the soil surface near the plants performed well under both dry and wet conditions. The sap nitrate test was more sensitive than total nitrogen measurement in indicating the timing of nitrogen uptake. Sap nitrate levels were influenced by nitrogen fertilizer application and soil water content. The general critical value of sap nitrate over the vegetative growing period was about 1000 ppm. The sap nitrate test appeared to be a very useful monitoring tool for plant nitrogen status. Further studies in the uses of sap nitrate test, especially the critical value, are needed. Use of leaf extension to detect the response of plants to nitrogen fertilizer applied was not successful. Nitrogen fertilizer application tended to accelerate leaf appearance under the low soil nitrogen status.Item Effect of cultivation on maize response to nitrogen fertilizer : a thesis presented in partial fulfillment of the requirements for the degree of Master in Applied Science in Soil Science, Institute of Natural Resources, Massey University, Palmerston North, New Zealand(Massey University, 2000) Munir, SulhadianaContinuous cultivation of arable soils results in the decline of 'soil quality' in terms of structural degradation and nutrient depletion. It decreases soil organic matter content, induces the leaching and gaseous losses of N through enhanced nitrification and denitrification, resulting in the depletion of nitrogen content of the soils. This will affect N availability, soil moisture retention, soil aeration and the activity of soil microorganisms. The objective of this study is to examine the effect of cultivation on the response of maize to N fertiliser. A glass house experiment was conducted using four soils. The soils included a permanent pasture soil and three maize / barley grown soils which have been cultivated for 6, 17 and 34 years. Maize plants were grown at six levels of N applied as urea (0 - 500 kg N/ha). The dry matter yield response to N application indicated higher maize growth for the pasture soil than for the cultivated soils at all levels of N application. Even at the highest level of N application (500 kg N/ha) the maize dry matter yield for the cultivated soil did not reach that for the unfertilised pasture soil. This indicates that N alone was not limiting the dry matter yield among the cultivated soils. It was hypothesised that the differences in the physical conditions among these soils may also be responsible for differences in dry matter yield. In the second experiment, pasture and the 34 year cultivated soils were incubated with poultry manure for eight weeks. The addition of poultry manure was to improve the physical conditions of the soil. A glasshouse experiment was then conducted to examine the effect of poultry manure addition on the growth of maize at five levels of N (0-400 kg N/ha) applied as urea. There was a clear visual indication of an improvement in the structure of the cultivated soil due to the incorporation of poultry manure. Addition of poultry manure increased the dry matter yields of maize plants both in the cultivated and the pasture soils. The dry matter yield of plants in the cultivated soils (in the presence of manure addition) was higher than the pasture soils at low levels of N application and similar yields were obtained at the higher rates of N application. Oxygen diffusion rate (ODR) values were higher for the pasture soil than the cultivated soil. The addition of poultry manure in the initial stages, however, decreased the ODR values in both soils which is attributed to the increased consumption of oxygen by the easily decomposable organic carbon in the poultry manure. With increasing time after incubation the ODR values slowly increased in the poultry manure treated soils indicating an improvement in soil structure. The study clearly demonstrated that the impact of cultivation on maize yield was partly due to poor soil physical conditions.Item The effect of nitrogen management and paddock history on growth and yield of barley (Hordeum vulgare L.) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Plant Science at Massey University(Massey University, 1985) Shuhaimen bin IsmailA field experiment was conducted during spring 1983/1984 at four adjacent sites on marginal the cropping soil Tokomaru silt loam to study the effect of nitrogen management and paddock history on growth and yield of barley (Hordeum vulgare L.) cv. Magnum. Six nitrogen treatments were tested in three replications in a randomised complete block design at each site. The treatments were no-N (control), 60 kg N/ha either applied at sowing, growth stage (G.S.) 3, G.S.6 or equally split between G.S.3 and G.S.6 and a higher rate based on soil test results (70-90 kg N/ha depending on site) applied at sowing. Site histories were immediately out of pasture and previously cropped with barley for 1 , 2 and 3 years. Crop nitrogen status was monitored by nitrate sap test and plant analysis. Control plot yield decreased almost linearly from 5.78t/ha directly out of pasture to 3.55 t/ha on the site previously cropped for three years. This indicated that regular cropping without fertiliser nitrogen on this soil could substantially reduce the yield of barley. Application of nitrogen significantly increased yield over control at all sites. The response in the first year of cropping was probably because of the low accumulation of nitrogen during the pasture phase on this soil. Average yield of plots receiving nitrogen were similar for the first two year of cropping (7.09 and 6.86 t/ha respectively) but declined rapidly for the third and fourth year of cropping (5.90 and 5.94 t/ha respectively). Plots receiving the high nitrogen rate were also unable to maintain yield as cropping increased. The yield decline could have been caused by deteriorated soil physical conditions under continuous cropping. Maintaining adequate nitrogen toward later stages of growth by late or split application was found to be as effective as applying the higher nitrogen rate at sowing especially as soil fertility reduced. Ear density was the main component affecting yield. Grain number/ear was also an important yield component for crop grown under lower fertility and was increased when nitrogen was applied at sites cropped for 3 and 4 years. There was differences between predicted yield based on soil test results and actual yield of control plots across the sites. Sap nitrate concentration showed a good relationship with total nitrogen analysis. Both measurements of plant nitrogen at earlier stages of growth were related to the yield. Highest yield (7t/ha) was found to be associated with 4.5% total nitrogen and >6000ppm sap nitrate concentration at about G.S.3.Item Effects of nitrogen fertiliser on the growth, development and yield of maize (Zea mays L.) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Plant Science(Massey University, 1974) Thom, Errol RossMaize has been grown in New Zealand for over a century. The traditional grain growing district has been Gisborne, where suitable environmental conditions prevail. Over recent years there has been a rapid expansion of maize production for grain, silage and greenfeed. For example, in the 1970/71 season (NZMAF estimates), 12,000 hectares of maize was grown for grain while in 1962/63 only about 3,000 hectares were grown; in the 1971/72 season 18,600 hectares were involved in grain production. Respective estimates for the 1972/73 and 1973/74 seasons were 16,300 and 17,800 hectares. Furthermore maize growing has now extended far beyond Gisborne with the Waikato, Bay of Plenty and Hawkes' Bay districts being regarded as major grain producing areas of New Zealand. Further south in the Manawatu and Canterbury high yielding crops of maize are also being grown for silage and greenfeed under suitable environmental conditions. Along with the upsurge in maize growing in these districts there has been the need for more agronomic information (Gooding, 1972) on the yield response, in terms of grain and total dry matter production; on the appropriate rate of nitrogen application and on the timing of the application for maximum response under the prevailing environmental conditions. With more maize being utilised in intensive animal production enterprises (Jagusch and Hollard, 1974) the quality of the dry matter produced assumes greater importance.Item Growth and nitrogen nutrition studies of onions (Allium cepa L.) : a thesis ... for the degree of Master of Horticultural Science in Horticultural Production at Massey University(Massey University, 1980) Ceesay, Momodou AlasanThe effect of nitrogen (N) fertilizer was studied in the field and in the greenhouse on the growth, development, maturation and storage life of onions (Allium cepa L.), cultivar "Pukekohe Long Keeper" (PLK). Samples were taken at specified harvest dates and morphological measurements, growth analysis and plant tissue analysis for nitrate-nitrogen (NO -N) and total nitrogen (total N) in the leaf blades, bulbs and roots of the onion plants were carried out. Also, high temperature storage for onions was investigated and compared with cool storage. Fresh and dry weight of the entire plant and the bulb dry weight increased with time to a maximum at the end of the growing period. Root dry weight, leaf dry weight, green leaf area and green leaf number increased with time then decreased as maturity approached. In general, whole plant fresh and dry weight and the plant parts, leaf and bulb, increased with increasing N fertilizer. Root dry weight was generally higher with the low N treatments than with the high N treatments. However, when N was too low, root growth was severely restricted. Low N rates tended to stimulate earlier bulb formation but delayed maturity. Very high N rates induced earlier maturity. Bulb weight and bulb diameter generally increased with increasing N fertilizer at the end of the growing season. Whole plant Relative Growth Rate (RGR) and bulb Relative Growth Rate (bulb RGR) were closely related. RGR and Leaf Area Ratio (LAR) decreased with time, however Net Assimilation Rate (NAR) was constant in the early growth stages but fluctuated in the later stages of growth. All the growth analysis parameters, RGR, NAR, LAR, Leaf Weight Ratio (LWR) and Specific Leaf Area (SLA), generally increased with increasing N fertilizer. The increase in RGR brought about by increases in N rate was mainly due to increases in LAR. The increase in LAR caused by increases in N levels was due mainly to increases in LWR. In general, NO -N and total N concentrations in the onion plant parts increased with increasing N fertilizer but declined as the plants advanced in age. Critical NO -N and total N concentrations for onions were determined from the relationship between relative growth and the NO -N and total N in the leaf blades, bulbs and roots. The NO -N concentration in the leaves and bulbs was found to be very low and appeared to be less reliable for determining the N status of the crop. The NO -N concentration in the roots was much higher, probably because nitrate is reduced in the roots in onions. However, analysing for total N, rather than NO -N, in the plant organs, in particular the leaf blades, is a much better method for monitoring the nitrogen status of an onion crop. The high N treatments generally removed more N than the low N treatments. A linear relationship was found between the bulb yield and the amount of N removed. For most soil conditions, 200 kg N/ha is considered an optimum level for onion production. There was little difference in storage life between bulbs stored under high temperature conditions and those under cool storage. Nitrogen fertilizer rates had no significant effect on bulb storability.Item The effect of applications of different nitrogen types and potassium on seed quality and AR37 endophyte presence at different spikelet and floret positions of perennial ryegrass cv. Halo(Massey University, 2014) Wang, MuyuNitrogen has been considered as an important nutrient in the terrestrial system. In the seed production of ryegrasses, one of the most popular pastures used in New Zealand and other temperate-zone areas, the application of nitrogen is responsible for improving seed yield and seed quality. Novel fungal endophytes are also now commonly used in perennial ryegrass pasture systems. The effect of different forms of nitrogen on seed quality and endophyte infection frequency and alkaloid concentration including spikelet/floret positional effects is also of interest to researchers. This study was designed to determine the effects of three nitrogen forms and potassium treatments (six in total) on the seed quality (purity, thousand seed weight (TSW), and germination) and AR37 endophyte presence in the offspring seedlings of the perennial ryegrass cv. Halo at three spikelet positions (top, middle and bottom). Also the effect of two nitrogen forms (nitrate and ammonium) at different floret positions was investigated. The two nitrogen forms (urea and nitrate) with potassium had a poorer seed quality compared with the control and all nitrogen treatments applied without potassium. Nitrogen application (any form by itself) did not affect TSW of ‘Halo’, but a reduction was found under urea or nitrate with potassium. Also, seed germination percentages were not affected by nitrogen type when compared with the control, but urea with potassium gave a lower germination than the three nitrogen forms alone; and nitrate with potassium was lower than just the urea treatment. In the purity test, urea applied alone had a higher pure seed percentage than the control and the other nitrogen forms applied alone, but, again, the nitrogen with potassium application had the poorest performance in the test. On the other hand, none of these seed quality parameters differed among the three spikelet positions (top, middle and bottom). Both nitrogen and potassium application and different spikelet positions did not affect endophyte content in the offspring seedlings of ‘Halo’.In the minor experiment, where seven floret positions and only two nitrogen forms (ammonium (NH4+)and nitrate (NO3-)) were compared, the individual seed weights of Halo in florets3, 4, and 7 under nitrate application were higher than that under ammonium. The seed weight in floret 7 wasthe only position lower than floret 1 and 2 when ammonium was applied. The germination percentages were not affected by the two nitrogen forms, nor were different floret positions. Further, nitrogen application also did not alter empty seed percentages (in frequency), but the basal florets produced less empty seeds. Differences in endophyte content between ammonium and nitrate applications were found only in floret position 1 where nitrate reduced endophyte. Also amongst florets under nitrate there was higher endophyte content in floret positions 2, 4 and 7.Item Measuring and modelling the fate of fertilizer and soil nitrogen in a cropping system : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science at Massey University(Massey University, 1983) Iqbal, Hayath MohammedFuture trends in New Zealand cropping, anticipate an increased use of fertilizer nitrogen (N). In order to more efficiently utilise N in cropping systems, a better understanding of the N processes and their significance under New Zealand conditions, is required. To achieve such understanding, several small scale experiments were conducted. Preliminary experiments, investigating the fate of N-15 urea applied to barley and oats, were conducted using soil cylinders. Total recovery of N-15 in plant and soil components varied between 50 to 90 percent. Initial urea N transformations were rapid, and most of fertilizer N uptake by plants occurred in the first five weeks following its application at sowing. Plants took up a greater proportion of their total N as native soil N. N-15 assay on soil and plant samples containing N-15 in excess of about 1 atom percent, was performed satisfactorily with emission spectrometry. The data obtained by the use of soil cylinders, were representative, particularly of short term field behaviour. A five-week study was undertaken to account for the extent and pattern of immobilisation and leaching of N-15 urea applied to a barley crop. Two irrigation treatments (wet and normal) were imposed. Approximately 90% of the applied N was recovered. One week after application, 86% of urea N had been hydrolysed, while after two weeks 36% of it had been immobilised into organic matter. The increased leaching of N from the wet lysimeters compared with the normal lysimeters was at the expense of plant N uptake, having little effect on the amount of N immobilised. Net mineralisation of native soil N was calculated as 1.2 kgN/ha/day. Using the data obtained from the preceding investigation, a five-week N model was developed. The model successfully predicted the increased leaching of fertilizer N from the wet compared with the normal lysimeters. The reduced plant uptake of fertilizer N, resulting from this increased leaching from the wet lysimeters, was also quite successfully modelled. The model indicated that the amount of fertilizer N leached was strongly dependent on the timing of rainfall in relation to the time of fertilizer application. A crop season model was developed by extending the five-week model to cover a full growth season of a barley crop, and the model was verified with data from a large scale field trial. The model prediction for N leaching losses, demonstrated better accuracy than for plant N uptake. The model has the potential to provide a continuous evaluation of possible adverse effects caused by unanticipated factors such as excessive rainfall, on plant N uptake. The crop season model was further developed to predict long term changes in the N cycle of a double cropping system, in a soil that was previously under pasture. The model predicted quite accurately the N loads as well as the N concentrations in tile drainage effusing from experimental field plots. In general, the measured and predicted data for nitrate concentrations in tile drainage of field plots indicated that nitrate concentrations in tile effluent usually exceed 15 to 20 mgN/litre, regardless of fertilizer addition. The addition of fertilizer could increase these levels two-fold but only for a short time. The utility of the model as a research tool was illustrated.