Balance sheet of phosphorus,sulphur and potassium in a long-term grazed pasture supplied with superphosphate

A balance sheet of P, S and K was constructed for a long-term trial which investigates the effects of three rates of superphosphate (9% P, 11% S) on pasture production on border-strip irrigated land grazed with sheep. A balance sheet of the inputs and outputs of P, S and K to the trial over a 38 year period showed that of the nutrients applied in fertiliser, only 51–59% of the P and 15–31% of the S were retained in the soil. Small amounts were lost in animal products (4–19% of the applied nutrients) but major losses were attributed to runoff of P as particulate matter (dung and soil particles) during irrigation and leaching of sulphate-S during irrigation. Losses of K from the site were small and had no effect on total soil K content. The distribution of soil nutrients across the border-strips was also investigated. The results showed that the concentrations of total soil P and S and exchangeable K were significantly greater at the sides of the irrigation borders than in the main strip area of pasture. This was caused by deposition of a disproportionate amount of dung and urine (and therefore nutrients) on the levees where the sheep tended to camp. It was calculated that with increasing superphosphate rates greater amounts of P were transferred to the levees due to the increased amounts of P being recycled via the animals (as a result of increased herbage P concentration, pasture production and stocking rate).     

Soil phosphorus pools with addition of fertiliser phosphorus in a long-term grazing experiment

Nutrient Cycling in Agroecosystems - Grasslands are a globally important use of land for food and fibre production, which often require the addition of phosphorus (P) fertiliser to maximise plant...     

高产小麦磷钾效应和适宜氮磷钾配比研究

黄泛冲积石灰性土壤在适宜施氮水平下磷钾不同用量及配比对小麦生长的影响表现为:(1)磷肥以中量施用水平(每公顷施用P2O5120kg)增产效果最好,分别比未施磷、低量施用水平(每公顷用P2O548kg)增产30.82%、20.27%,高量施用水平(每公顷施用P2O5192kg),虽然比中量施用水平表现出增产,但增产幅度很小,只有2.85%;(2)钾肥对小麦的增产效应小于磷肥,只有在施用磷肥的基础上配施钾肥,才能使钾的效应得到充分发挥;(3)小麦全生育期氮磷钾施用比例1∶0.5∶0.5为最佳,每公顷施用N240kg、P2O5120kg、K2O120kg效益最高。     

Influence of urea fertiliser formulation, urease inhibitor and season on ammonia loss from ryegrass

This paper reports the results of experiments to determine whether ammonia (NH₃) loss can be reduced and nitrogen (N) use efficiency improved by using two relatively new commercial urea formulations rather than granular urea and urea ammonium nitrate. Four nitrogen treatments were applied at a rate of 40 kg N ha^?1: granular urea, ‘Green Urea? 14’ [containing 45.8 % N as urea and ‘Agrotain^®’ (N-(n-butyl) thiophosphoric triamide) @ 5 L t^?1 of urea as a urease inhibitor], ‘Nhance’, a fine particle spray [containing 46 % N as urea, ‘Agrotain’ @ 1 L t^?1 of urea and gibberellic acid (applied at a rate of 10 g ha^?1)] and urea ammonium nitrate in solution (UAN) surface applied. Ammonia loss was determined in autumn and spring using a micrometeorological method. In autumn, use of the Green Urea and Nhance reduced NH₃ loss from the 30 % of applied N lost from the granular urea to 9 and 23 % respectively. Loss from all treatments in spring was very small (<2 % of applied N), because 4 mm of rain fell within 24 h of application onto an already wet site. The use of the Nhance and Green Urea instead of granular urea did not result in increased agronomic efficiency or recovery efficiency of the applied N, and this is most likely due to the presence of sufficient available N from both fertiliser application and the soil. A ¹⁵N study recovered 72.8 % of the applied N in the plants and soil, and showed that 30 % of the total N taken up by the plant was derived from the fertiliser, and 70 % from the soil.     

Changes in the cycling of nitrogen, phosphorus, and potassium in a dairy farming system

The objective of this study was to quantify nitrogen (N), phosphorus (P), and potassium (K) use and cycling in a dairy farming system. The data were collected from the experimental farm at the National Institute of Livestock and Grassland Science in Tochigi Prefecture, Japan, using about 11 ha of forage crop fields and about 30 dairy cows. Forage crops grown in the field were ensiled and offered to the cows, and the subsequent compost from the animals’ excretion was applied to the field. The dairy farming system consisted of soil/crop, feed storage, animal, and compost components. Nutrient inputs and outputs and flows of the soil–plant–animal pathway for the whole farm and each component were measured for 5 years. Nutrient utilization was evaluated using nutrient balances, use efficiencies, and cycling indices. The 5 year average nutrient balances and nutrient use efficiencies of N, P, and K for the whole farm (kg ha^?1 year^?1) were 378, 97, and 199 and 0.25, 0.19, and 0.18, respectively. The characteristics of nutrient balances and use efficiencies for each component differed among N, P, and K. The average cycling indices of N, P, and K were 0.12, 0.11, and 0.37, respectively. Significant positive relationships between use efficiencies and cycling indices were observed in N and K. Year-to-year variations in flows were relatively large for compost application. The results suggested that improving N balance would be the most effective option for solving many of the environmental problems related to dairy farming.     

Recovery of 15N-labelled fertiliser by a perennial ryegrass seed crop and a subsequent wheat crop

Large amounts of nitrogen (N) fertiliser (150–200 kg N/ha) are currently being applied to perennial ryegrass (Lolium perenneL.) seed crops in New Zealand. Due to increasing requirements for efficient use of N fertilisers and minimising nitrate contamination of the environment, a field experiment was established using ¹⁵N-labelled fertiliser to follow the fate of applied N. Urea-¹⁵N was applied to a perennial ryegrass seed crop in April (30 kg N/ha), August (30 kg N/ha), September (60 kg N/ha) and October (60 kg N/ha). The urea-¹⁵N was applied in solution and watered in to minimise volatilisation loss. At the time of harvest (December), 9% of the applied ¹⁵N was in the seed, 29% in the straw, 19% in the roots and 39% in the soil organic matter. Losses of ¹⁵N were minimal as the N was applied in several applications, each one at a relatively low rate, and at times when leaching was unlikely to occur. Ryegrass plants used a greater proportion of the N applied in September and October (61–65%) compared with that applied in April (44%). Consequently more N was recovered from the soil in the autumn application (57%) than from the September and October applications (28–44%). The availability of the residual fertiliser N to a subsequent wheat (Triticum aestivum L.) crop was studied in a glasshouse experiment. The residual fertiliser N was present in the soil and ryegrass roots and stubble. The wheat plants only recovered 7–9% of this residual N. Most of the N taken up by the wheat came from the soil organic N pool. Overall, applying a total of 180 kg N/ha to the ryegrass appeared to have minimal direct impact on the environment. In the short term N not used by the ryegrass plants contributed to the soil organic N pool.     

The effect of fertiliser and grazing on nitrogen export in surface runoff from rain-fed and irrigated pastures in south-eastern Australia

Nutrients, including nitrogen (N), exported from agricultural systems contribute to eutrophication and the development of algal blooms. Understanding the relative effect of farm management on nutrient export will indicate the extent to which farmers can potentially mitigate this process. Six years of monitoring surface runoff from rain-fed and irrigated dairy pastures was carried out in south-eastern Australia. Over the monitoring period, the flow-weighted mean annual total N (TN) concentrations in runoff varied between 8.2 and 29 mg/l for rain-fed pasture and 8.7 and 58 mg/l for irrigated pasture. An additive component model describing N concentrations separated the management (grazing and fertiliser) and year effects from other processes. The model accounted for 40 and 47% of the variation in N concentrations for the rain-fed and irrigated pastures, respectively. While fertiliser application, grazing and year had a significant effect on concentrations, other variables that are not necessarily under management control significantly affected N export. With current knowledge, improved management of pasture-based systems such as improved timing of fertiliser application and grazing relative to runoff may only result in a small decrease in N export. The remainder of the variability was attributed to environmentally mediated changes of N concentrations in runoff water. The collection of more detailed information on environmental parameters including soil moisture and soil temperature is proposed, to enable a better prediction of N concentrations and therefore improved understanding of potential management strategies.     

Ammonia volatilization from grassland receiving nitrogen fertilizer and rotationally grazed by dairy cattle

The micrometeorological mass balance method was used to measure ammonia (NH₃) volatilization from rotationally grazed swards throughout the 1987 and 1988 growing seasons. In both years the swards were dressed with calcium ammonium nitrate (CAN) split over 7 dressings. In 1987 the sward received a total of 550 kg N ha^–1, in 1988 a total of 550 or 250 kg N ha^–1. For the 550 kg N ha^–1 treatments there were 8 and 9 grazing cycles, respectively, in 1987 and 1988 and 7 for the 250 kg N ha^–1 treatment. Losses from the 550 N sward were 42.2 and 39.2 kg N ha^–1 in 1987 and 1988, respectively; this was equivalent to 8.5 and 7.7% of the N returned to the sward in the excreta of the grazing cattle. The NH₃ loss from the 250N sward was 8.1 kg N ha^–1 in 1988, which was equivalent to 3.1% of the N returned to the sward in excreta during the growing season. There was a wide variation in NH₃ volatilization between the individual grazing periods. This indicates the necessity of continued measurements throughout the growing season to obtain reliable data on NH₃ volatilization. Soil humidity is suggested to be a key factor, because emissions were high from wet soil, and low from drier soil. Results of a Monte Carlo simulation study showed that the measured NH₃ loss from the 250 and 550 N swards had a standard deviation of 13 and 5% of the mean, respectively.     

Stratification of soil phosphorus,pH, and macro-cations under intensively cropped grass ley

The large amounts of nutrients applied to and removed from soil by intensive grass production may cause quick changes in the nutrient pools available to plants and exposed to leaching and runoff losses. Stratification of applied nutrients is especially important for phosphorus (P), which moves slowly in soil. To study the vertical distribution of extractable nutrients and soil pH in different types of ley soil, P fertilisers were incorporated or placed prior to sowing or broadcast annually at ten sites for 3 years. Then the soils were sampled in several layers 2.5 or 5 cm deep and analysed for pH and the concentrations of phosphorus, potassium (K), calcium (Ca), and magnesium (Mg) extractable with acid ammonium acetate. In mineral soils, broadcast P mainly remained within the uppermost 2.5 cm of soil, in which the concentrations of extractable P more than doubled during the study period. When commonly used NK and NPK fertilisers were applied, the uppermost 5 cm of soil was acidified by about 0.5 pH units and its Ca value decreased by about 25%. Broadcast K enriched a thin surface layer even if the K balance was negative. Estimation of the concentration of dissolved phosphate in runoff suggested that the high P losses that are possible at excessive levels of soil test P can be diminished by perennial grasses supplied with abundant water and other nutrients. Surface-applied P appeared to increase the losses, but even a shallow placement seemed to prevent them efficiently if all fertiliser granules become covered with soil.     

Estimation of phosphorus and potassium concentrations in Bermudagrass

Equations were developed to estimate concentrations of phosphorus and potassium for Coastal bermudagrass [Cynodon dactylon, (L.) Pers.] as related to applied nutrient level and harvest interval. Data from several field studies were used in the analysis. Estimates from these agronomic studies agreed with data from fertilizer and waste application for several locations. Concentrations of phosphorus and potassium decreased linearly with harvest interval (up to 6 weeks) and increased exponentially with nutrient level. This information should be relevant to crop production and environmental quality.     

Double-cropping annual ryegrass and bermudagrass to reduce phosphorus levels in soil with history of poultry litter application

Long-term application of poultry litter may result in excessively high soil phosphorus (P). This field study determined the potential of ‘Coastal’ bermudagrass overseeded with ‘Marshall’ annual ryegrass and harvested for hay to reduce the level of Mehlich-3 extractable P (M3-P) that had accumulated in a Savannah soil due to a 30-year history of broiler litter application to bermudagrass, as well as antecedent litter rates of 0, 4.48, 8.96, 17.9, and 35.8 Mg ha⁻¹ in 1999–2001. Following the cessation of litter, the plots were overseeded in fall 2001–2003 and fertilized in summer with 268 kg N ha⁻¹ as NH₄NO₃. Applying 8.96 Mg ha⁻¹ litter significantly elevated M3-P in surface soil (0–15 cm depth) from about 183 to 263 mg kg⁻¹. Annual dry matter (DM) yield and P uptake generally increased as litter rate increased up to 17.9 Mg ha⁻¹. Analysis of M3-P at four sampling dates from October 2002 to April 2004 found no significant effect of forage system or its interaction with litter rate, and levels in both systems decreased by about 25, 27, 22, 26, and 29% at the five litter rates, respectively. Ryegrass–bermudagrass significantly increased DM yield and P uptake, but did not translate to reductions in M3-P, as compared to bermudagrass winter fallow. With no further litter additions and five harvests per year, both forage systems removed about 49 kg ha⁻¹ P with a DM yield of 15 Mg ha⁻¹ and reduced M3-P by about 26 mg kg⁻¹ annually. Bermudagrass performance is important in the remediation of high soil P.

Finger millet response to nitrogen,phosphorus and potassium in Kenya and Uganda

Finger millet (Eleusine coracana (L.) Gaertn) is an important food crop of semi-arid to sub-humid Africa where little is known of its response to applied nutrients. Yield responses to nitrogen (N), phosphorus (P) and potassium (K) together with a diagnostic treatment (S, Mg, Zn, B) were determined from field research conducted in western Kenya and eastern and central Uganda. Grain yield was not affected by applied nutrients in some sites in Kenya, likely due to other prevailing stresses. Grain yield increased with N application for all sites and years in Uganda by a mean of 127% from the no N treatment (0 N) yield of 1.00 Mg ha^?1. Grain yield increases ranged from 0.76 to 1.40 Mg ha^?1 with 30 kg N ha^?1 applied, with little added increase with >60 kg N ha^?1. The mean economically optimal rate for N in Uganda was 72 and 43 kg N ha^?1 with expected net returns to N of 166 and 279 $ ha^?1 when the N cost to grain value was 3 and 9 kg kg^?1, respectively. Yield was increased with P and K application at two of four production areas of Uganda. Yield was increased by >20% with application of Mg–S–Zn–B in addition to N–P–K for all sites in Uganda with foliar concentrations indicating possible S and B deficiency. There is great profit potential in Uganda, and less for Kenya for N, but not for P and K, application to finger millet. Response to S and B needs further exploration.     

Interactions between nitrogen,phosphorus and potassium determine growth and N<Subscript>2</Subscript>-fixation in white clover and ryegrass leys

Variations in yield, N₂ fixation and above-ground accumulation of nitrogen (N), phosphorus (P) and potassium (K) in white clover and ryegrass grown separately or in mixture were investigated under field conditions over two consecutive years at different supplies of N, P and/or K. Ryegrass-clover mixtures consistently out-yielded the pure stand clover and pure stand ryegrass in terms of dry matter. Improved N supply favoured ryegrass, and ryegrass in mixture with clover accumulated substantially higher amounts of N, P and K than ryegrass in pure stand. Conversely, the growth of white clover in mixture with grass was significantly depressed by N application, particularly when P and K were also applied. Plots of dry matter, N, P and K in white clover versus ryegrass in mixtures followed log-normal relations demonstrating the superior responsiveness of ryegrass to improved availability of N, P and/or K. Although competition for P and/or K reduced the N₂ fixation rate in the mixture, the effect on the total above-ground N accumulation was insignificant. The proportions of P and K in the shoot dry matter of ryegrass in pure stand were only half of those of ryegrass in mixture with clover, while white clover co-cultivated with ryegrass had lower P concentration in dry matter, showing a P deprivation of clover growing in mixture with grass. Na was able to replace K under the competitive conditions in the mixture. In conclusion, the results show that growth and nutrient acquisition of clover and ryegrass interact in a complex manner involving competition, facilitation and complementarity.     

Response of rice cultivars to phosphorus supply on an oxisol

Genotypic differences in absorption or utilization of P might be exploited to improve efficiency of fertilizer use or to obtain higher productivity on P-deficient soils. The objective of this study was to evaluate responses by 75 genotypes of upland rice (Oryza sativa L.) to two soil P levels in two field experiments. In the first experiment, soil P levels (Mehlich 1) were 1.5 mg kg^–1 and 5 mg kg^–1, and in the second experiment, 3 mg kg^–1 and 4.7 mg kg^–1 of soil, respectively. Rice cultivars differed significantly in shoot dry matter production at flowering, grain yield, and plant P status. Based on a grain yield efficiency index, cultivars were classified as P-efficient or P-inefficient. Shoot dry matter was more sensitive to P-deficiency but was not related to grain yield. Phosphorus use efficiency was higher under the low P treatment. Phosphorus uptake was significantly correlated with dry matter, P concentration and P-efficiency ratio. Results of this study indicate that genetic differences in P-use efficiency exist among upland rice cultivars and may be exploited in breeding programs.Contribution from National Rice and Bean Research Center of EMBRAPA, Goiania, Goias, Brazil and Appalachian Soil and Water Conservation Research Laboratoy, Beckley, WV, USA.     

Pot experiments with Italian ryegrass: Yields and evaluation of soil potassium status with different methods of applying potassium fertilizer

Italian ryegrass (Lolium multiflorum) is studied in pot experiments on a soil of low potassium status. Different methods of applying potassium are compared which result in different dry-matter yields in successive cuts; the effect of the different K applications are also compared on the decreasing or improving evolution of the K soil status during and after the cropping. The compensation with amounts of K corresponding to the K uptake of the previous cut is particularly interesting in terms of fertilizer efficiency.     

Nitrogen,phosphorus and potassium balances and cycles of Swiss agriculture from 1975 to 2008

Intensification of Swiss agriculture after 1950 led to an increase in productivity and a range of environmental and health problems provoked by growing inputs of nitrogen (N), phosphorus (P) and potassium (K) into the agricultural cycle. In 2008, farm-gate balances showed surpluses of 108 kg N ha⁻¹, 5.5 kg P ha⁻¹ and 28 kg K ha⁻¹ for Swiss agriculture. Nutrient surpluses rose between 1975 and 1980 and then decreased significantly until 2008, with percentage reductions being higher for P (80%) and K (54%) than for N (27%). The introduction of direct payments for ecological programmes such as integrated production in 1993 led to a more pronounced decrease in nutrient surpluses for several years, until most farmers had joined these programmes. Lower surpluses could primarily be attributed to reductions in mineral fertilizer use and N deposition. Biological N fixation and atmospheric deposition contributed most to the uncertainty in calculating nutrient balances. N cycle was characterized by substantial inputs into and outputs out of the agricultural sector, whereas P and K cycles were more closed. In future, nutrient balances at a regional level are required to identify areas with high surpluses. In Switzerland, a further reduction in surpluses could be achieved by better feeding strategies and an improved fertilizer management, mainly of animal manure.     

Dung pads increase pasture production,soil nutrients and microbial biomass carbon in grazed dairy systems

In grazing systems dung is an important source of nutrients which can increase soil fertility and contribute to nutrient cycling through increased pasture production. Changes in soil chemical and biological properties and pasture production were measured below and around dung pads created in the field. Almost 65% of the total dung P remained after 45 days and about two-thirds of the pad fresh weight had disappeared in that time, indicating that physical degradation is the mechanism of incorporation of dung P. All the pads bar one were completely degraded by 112 days. At this time, soil pH and EC increased under dung pads as did Olsen extractable inorganic phosphorus (Pi) and total phosphorus (Pt), with these changes observed at 0–5 and 5–10 cm depths. Bicarbonate extractable soil organic phosphorus (Po) was not affected by dung and the observed differences in soil Po:Pi ratios were largely influenced by the substantial addition of inorganic P from dung. Dung increased the P buffering capacity of the 0–5 cm soil samples collected at the end of the experiment, potentially contributing to the increased extractable soil P measured under the pads. Dung also changed soil properties in 0–10 cm samples with increases in soil pH, EC, Colwell P and Colwell K recorded even long after the dung had completely disappeared. Microbial biomass carbon increased under dung pads in the 0–10 cm soil samples in the first 45 days after pads were applied. Total herbage production and ryegrass biomass increased significantly under and around the pads by 112 days after dung was applied. The botanical composition changed significantly with increased ryegrass contents observed, but only under the dung pads. This experiment demonstrated that increases in pasture around dung pads in the field are not solely due to animal rejection.     

ICP-OES法测定有机肥料中钾和磷

<正>有机肥料中磷和钾元素的测定采用NY525—2002标准,其中磷采用磷钼黄分光光度法测定、钾采用火焰光度计法测定[1]。该方法非常繁琐,不易操作,且测定周期长,精密度差,检出限高。电感耦合等离子发射光谱(ICP-OES)是近几年来应用广泛的高灵敏度的简便分析仪器之一,非常适用     

Response of sorghum to fertilizer phosphorus and its residual value in a Vertisol

The response of crops to added P in Vertisols is generally less predictable than in other soil types under similar agroclimatic conditions. Very few studies have considered the residual effects of P while studying responses to fresh P applications. Field experiments were conducted for three years to study the response of sorghum to fertilizer P applied at 0, 10, 20 and 40 kg P ha^–1, and its residual value in a Vertisol, very low in extractable P (0.4 mg P kg^–1 soil), at the ICRISAT Center, Patancheru (near Hyderbad), India. In order to compare the response to fresh and residual P directly in each season, a split-plot design was adopted. One crop of sorghum (cv CSH6) was grown each year during the rainy season (June-September).The phenology of the sorghum crop and its harvest index were greatly affected by P application. The days to 50% flowering and physiological maturity were significantly reduced by P application as well as by the residues of fertilizer P applied in the previous season. In the first year of the experiment, sorghum grain yield increased from 0.14 t (no P added) to 3.48 t ha^–1 with P added at the rate of 40 kg P ha^–1. Phosphorus applied in the previous year was 58% as effective as fresh P but P applied two years earlier was only 18% as effective as fresh P.