Effect of defoliation and phosphorus concentration in the sown seed on the response of swards of annual pasture legumes to superphosphate applications

The relationship between dry matter (DM) herbage yield and the level of superphosphate applied to the soil (soil P) was measured for swards of annual pasture legumes in four glasshouse and two field experiments. A single cultivar of one species was used in each experiment. The swards were either uncut, or cut at weekly intervals to a height of 1.5 to 3 cm from the soil surface from about one month after sowing. The sown seeds of each species were of the same size but contained different P concentrations (seed P).For the glasshouse experiments, defoliation reduced DM herbage yields of the species (Trifolium subterraneum, T. balansae, Medicago polymorpha andOrnithopus compressus) by between 20 to 50% two months after sowing, and by 50 to 75% three months after sowing. Higher seed P increased DM herbage yields two months after sowing by about 25% for the lowest soil P level and by 15% for the highest soil P level. Three months after sowing the values were 12 and 8%.In one field experiment, compared with uncut swards, the DM herbage yields for the weekly cut swards ofT. subterraneum were reduced by up to about 5% for the lowest soil P, compared with up to 25% for the highest soil P. Corresponding reductions forM. polymorpha swards in the other field experiment were about 15 and 20%. For the weekly cut swards, high seed P produced large increases in the cumulative DM yields of the weekly cut herbage. Increases for low soil P were about 300% at 2.5 months after sowing and 30% at 4.5 months after sowing. Corresponding values for high soil P were 100 and 20%. However, higher seed P produced only small (zero to 15%) increases in total DM yield of uncut and weekly cut swards (for the weekly cut swards, total DM yield was the cumulative yields of the weekly cut herbage plus the DM yield of the plant residues that were below the cutting height of the mower). Compared with uncut swards, seed production, measured forM. polymorpha only, was reduced by 40% when the swards were regularly cut. Higher seed P increased seed production of uncut swards by 40% for the lowest soil P level and by 25% for the highest soil P level. Corresponding values for the weekly cut swards were 30 and 20%.     

The combined effect of fertiliser nitrogen and phosphorus on herbage yield and changes in soil nutrients of a grass/clover and grass-only sward

The combined effect of reduced nitrogen (N) and phosphorus (P) application on the production of grass-only and grass/clover swards was studied in a five-year cutting experiment on a marine clay soil, established on newly sown swards. Furthermore, changes in soil N, P and carbon (C) were measured. Treatments included four P (0, 35, 70 and 105 kg P ha^–1 year^–1) and three N levels (0, 190 and 380 N kg ha^–1 year^–1) and two sward types (grass-only and grass/clover). Nitrogen was the main factor determining the yield and quality of the harvested herbage. On the grass-only swards, N application increased the DM yield with 28 or 22 kg DM kg N^–1, at 190 or 380 kg N ha^–1 year^–1, respectively. The average apparent N recovery was 0.78 kg kg^–1. On the grass/clover swards, N application of 190 ha^–1 year^–1 increased grass production at the cost of white clover, which decreased from 41 to 16%. Phosphorus application increased grass yields, but did not increase clover yields. A positive interaction between N and P applications was observed. However, the consequences of this interaction for the optimal N application were only minor, and of little practical relevance. Both the P-AL-value and total soil P showed a positive response to P application and a negative response to N application. Furthermore, the positive effect of P application decreased with increasing N application. The annual changes in P-AL-value and total soil P were closely related to the soil surface surplus, which in turn was determined by the level of N and P application and their interaction. The accumulation of soil N was similar on both sward types, but within the grass-only swards soil N was positively affected by N application. The accumulation of organic C was unaffected by N or P application, but was lower under grass/clover than under grass-only.     

The effect of water supply on the response of subterranean clover,annual medic and wheat to superphosphate applications

The effect of water supply on the response of subterranean clover (Trifolium subterraneum), annual medic (Medicago polymorpha) and wheat (Triticum aestivum) to levels of phosphorus (P) applied to the soil (soil P) was studied in four glasshouse experiments. P was applied as powdered superphosphate. In one experiment, the effect on plant yield of P concentration in the sown seed (seed P) was also studied. There were two water treatments: the soil was returned to field capacity, by watering to weight, either daily (adequate water, W1) or weekly (water stress, W2). In three experiments: (i) P concentration or content (P concentration × yield) in plant tissue was related to plant yield, and (ii) soil samples were collected before sowing to measure bicarbonate-extractable P (soil test P) which was related to subsequent plant yields.Compared with W1, water stress consistently reduced yields of dried tops and the maximum yield plateau for the relationship between yield and the level of P applied, by up to 25 to 60% in both cases. Compared with W1, the effectiveness of superphosphate for producing dried tops decreased for W2 by 11 to 45%, for both freshly-applied and incubated superphosphate. Consequently in the field, water supply, which varies with seasonal conditions, may effect plant yield responses to freshly — and previously — applied P fertilizer.Seed P increased yields, for W1, by 40% for low soil P and 20% for high soil P; corresponding values for W2 were 20 and 12%. Consequently proportional increases due to seed P were smaller for the water-stressed treatment.The relationship between yield and P concentration or content (internal efficiency of P use) differed for W1 and W2, so that the same P concentration or content in tissue was related to different yields. Estimating the P status of plants from tissue P values evidently depends on water supply, which in the field, differs in different years depending on seasonal conditions.The relationship between yield and soil test P differed for W1 and W2. Predicting yields from soil test P can only provide a guide, because plant yields depend on both P and water supply, which in the field may vary depending on seasonal conditions.     

Potassium uptake and requirement in organic grassland farming

Use of mineral fertilizers is restricted in organic farming. The aim of the present paper was therefore to study whether potassium (K) limits yields in Norwegian organic grasslands. The K status in soil and herbage on 26 organic farms was investigated, and the response to K application in six fertilization experiments was explored. Further, the relationship between soil K analyses and K release from soil was examined. K application to grassland on the investigated farms was generally low, giving negative field K balances on 23 of the farms. The soils were classified as low or intermediate in readily available K (K_AL) on 23 of the farms. The mean K concentration for herbage samples from the first cut on these farms was 18.0 g K kg⁻¹ dry matter. In fertilization experiments, K application increased the K concentration in herbage. However, there was no significant effect on yield, even when K concentration in herbage on plots without K application was low. The lack of significant yield response to K application can be explained by low amounts of crop-available nitrogen (N). There was a tendency for increased plant uptake from reserve K with increasing values of acid soluble K (K–HNO₃) in soil. Separate K analyses of timothy (Phleum pratense) and red clover (Trifolium pratense) revealed that red clover showed better competitiveness for K than timothy in leys where N supply was limited.     

Effect of fertilizer type,sampling depth,and years on Colwell soil test phosphorus for phosphorus leaching soils

The relationships between (i) soil test phosphorus (P) (Colwell sodium bicarbonate procedure) and the level of P applied (from 0 to 1000 kg total P ha^–1) (relationship 1), and (ii) yield and soil-test P (relationship 2, the soil P test calibration), were measured in two field experiments on very sandy, P-leaching soils in the high rainfall (> 800 mm annual average) areas of south-western Australia. The soils were humic sandy podzols, or haplohumods, comprising 97% sand (20 to 2000 m). The experiments started in April 1984 and were terminated at the end of 1990. Soil-test P, measured on soil samples collected to 5, 10 and 25 cm depth each January in the years after P application, was related to yields of dried clover (Trifolium subterraneum) herbage measured later in each year. The four P fertilizers studied were single superphosphate, coastal superphosphate (made by adding, just before granulation, extra rock phosphate together with elemental sulphur while manufacturing single superphosphate), apatite rock phosphate, and Calciphos.Relationship (1) was adequately described by a linear equation (R² > 0.80, most being > 0.90). The slope coefficient estimates the extractability of P from the soil by the Colwell procedure, and is called extractability. Relationship (2) was adequately described by the Mitscherlich equation (R² > 0.75, most being > 0.90). For relationship (2), use of percentage of the maximum (relative) yield eliminated differences due to different maximum yields and yield responses (maximum yield minus the yield for the nil-P treatment). Soil test P ranged from about 4 to 150 g Pg^–1 soil. Soil test P and extractability were generally higher for samples of the top 5 cm of the soil than the top 25 cm, and were largest for single superphosphate and lowest for apatite rock phosphate. Both extractability (relationship (1)) and the curvature coefficient of the Mitscherlich equation (relationship (2)), differed for different P fertilizers and different soil sample depths. The curvature coefficient also differed for different yield assessments (harvests) in the same or different years. Different soil P test calibrations were required for different P fertilizers, soil sample depths and harvest in the same or different years. It is concluded that soil P testing provides a crude estimate of the current P status of P-leaching soils in Western Australia.     

Agro-ecological nitrogen management in soils vulnerable to nitrate leaching: a case study in the Lower Suwannee Watershed

Environmental benefits associated with reduced rates of nitrogen (N) application, while maintaining economically optimum yields have economic and social benefits. Although N is an indispensable plant nutrient, residual soil N could leach out to contaminate groundwater and surface water resources, particularly in sandy soils. A 2-year field study was conducted in an established bermudagrass (Cynodon dactylon) pasture in the Lower Suwannee Watershed, Florida, to evaluate N application rates on forage yield, forage quality, and nitrate (NO₃-N) leaching in rapidly permeable upland sandy soils. Four N application rates (30, 50, 70, and 90 kg N ha⁻¹ harvest⁻¹) corresponding to 0.33, 0.55, 0.77 and IX, respectively, of recommended N rate (90 kg N ha⁻¹ harvest⁻¹) for bermudagrass hay production in Florida were evaluated vis-à-vis an unfertilized (0 N) control. Suction cups were installed near the center of each plot at two depths (30 and 100 cm) to monitor NO₃-N leaching. The grass was harvested at 28 days intervals to determine dry matter yield, N uptake, and herbage nutritive value. Nitrogen application at the recommended rate produced the greatest total dry matter yield (~18.4 Mg ha⁻¹ year⁻¹), but a modeled economically optimum N rate of ~57 kg N ha⁻¹ harvest⁻¹ (~60% of the recommended N rate) projected an average dry matter yield of ~17.3 Mg ha⁻¹ year⁻¹, which represents >90% of the observed maximum yield. Nitrogen application increased nutritive quality of the grass, but increases in N application rate above 30 kg N ha⁻¹ did not result in significant increases in in vitro digestible organic matter concentration, and tissue crude protein was not significant above 50 kg N ha⁻¹. Across the sampling period, treatments with N rates ≤50 kg N ha⁻¹ harvest⁻¹ had leachate NO₃-N concentration below the maximum contaminant limit of <10 mg l⁻¹. Conversely, applying N at rates ≥70 kg N ha⁻¹ harvest⁻¹ resulted in leachate N concentration that exceeded the maximum contaminant limit, and suggest high risk of impacting groundwater quality, if such rates are applied to soils with coarse (sand) textures. The study demonstrates that recommendation of a single N application rate may not be appropriate under all agro-climatic conditions and, thus, a site-specific evaluation of best N management strategy is critical.     

Effect of a wide range of nitrogen applications on herbage nitrate content in long-term fertilizer trials on all-grass swards

In three long-term nitrogen fertilization experiments with total applications of up to 1120 kg N per ha per year and cutting at a DM yield of 2 to 2.5 t per ha, the herbage nitrate content of all-grass swards was studied for each cut. At applications of 60 kg N per ha per cut, with a maximum of 360 kg N per ha per year, there was little or no increase in nitrate content. At applications of 80 kg N per ha per cut, totalling 400–560 kg N per ha per year, 3% of the samples had nitrate contents higher than 0.75% N0₃. At applications of 120 and 160 kg N per ha per cut, totalling 600–1120 kg N per ha per year, 61 and 67% of the samples exceeded 0.75% N0₃, respectively. The excess nitrate did not occur in the spring cuts, but for the most part in the summer cuts and seldom in the autumn cuts. This may explained by a positive relationship between temperature and herbage nitrate content, under favourable moisture conditions. In warm but dry periods there was no relationship and nitrate contents were low.     

Influence of pH,time and rate of application on phosphate rock dissolution and availability to pastures

The agronomic effectiveness of an unground reactive phosphate rock from Sechura, Peru, was compared with that of monocalcium phosphate in a severely P deficient and highly P retentive soil (vitrandept) over a period of three years. Soil pHs were adjusted to pH 5.1, 5.3, 5.6 and 6.4. The sward consisted mostly of ryegrass (Lolium perenne) and white clover (Trifolium repens). Fertilisers were applied at six rates at pH 5.3 and three rates at other pHs in the first year. For two of the rates fertilisers were reapplied in the second year. Dry matter yields, P uptake and ground cover of clover were determined during the experimental period. In phosphate rock treated plots a negative linear relationship was obtained between soil pH and the logarithm of yield. The agronomic effectiveness of phosphate rock relative to monocalcium phosphate increased with time at all pHs. Calculated at fertiliser rates which produced near maximum yields, relative agronomic effectiveness at soil pHs 5.1, 5.3, 5.6 and 6.4 were respectively 58, 60, 18, and 5 in year one; 118, 125, 77 and 38 in year three. At pH 5.3, as the rate of application increased the relative agronomic effectiveness of the phosphate rock generally decreased in year one but was enhanced in the intermediate rates in years two and three. The data for ground cover of clover gave a similar trend to that for herbage yield and P uptake.     

Comparative responses of annual pasture legume species to superphosphate applications in medium and high rainfall areas of Western Australia

The comparative phosphorus (P) requirement of different annual pasture legume species was measured in seven field experiments in south-western Australia. Superphosphate was applied once only, at the start of each experiment. The duration of the experiments was from one to three years. The amount of P required to produce 90% of the maximum yield of each legume was used to estimate the comparative P requirements of the legumes at each harvest. Ornithopus spp. (O. compressus, O. perpusillus andO. pinnatus) required less P thanTrifolium subterraneum, the most widely sown pasture legume in Western Australia. The P requirements ofMedicago polymorpha varied with soil type when compared to that ofT. subterraneum. M. polymorpha required less P on a soil with a neutral pH value, but had a similar P requirement on a more acidic soil.M. murex, generally required more P thanT. subterraneum. In some experiments, the comparative P requirement of the different legumes varied for different harvests.At each harvest in each experiment, the relationship between yield and P concentration in tissue (internal efficiency curves) usually differed for different legumes. Presumably different legumes take up P from the soil at different rates within each harvest, and utilize the absorbed P differently to produce herbage and seed. The exceptions were that similar internal efficiency curves were measured forO. compressus andT. subterraneum in one experiment, and three cultivars ofO. compressus in another experiment.     

The current and residual value of superphosphate for lupins grown in rotation with oats and wheat on a deep sandy soil

In a field experiment on a deep pale-yellow sand in a 600 mm per annum rainfall Mediterranean environment of south-western Australia, six levels of phosphorus (P) as superphosphate (O up to 546 kg P ha^–1) were applied once only, to the soil surface, before sowing lupins (Lupinus angustifolius). The lupins were grown in a continuous arable cropping rotation with, in successive years, oats (Avena sativa), wheat (Triticum aestivum), lupins. Five such rotations were started in the experiment from 1985 to 1989. The experiment continued until the end of 1990.The relationship between lupin seed (grain) yields and the level of P applied was measured in the year of P application for five successive years (1985 to 1989). The relationship had the same general form but it varied between years, largely due to different maximum yields (yield plateaux) in each year.The residual value of superphosphate applied three years previously was measured for lupins on two occasions (1988 and 1989) relative to superphosphate applied in the current year. The residual values was different in the two years. The superphosphate applied three years previously was about 30% as effective as freshly applied superphosphate in 1988, and 12% as effective in 1989.At each harvest, the relationship between grain yield and the P concentration in the grain differed for different species. However, for each species at each harvest, the relationship was similar regardless of when the P was applied in the previous years. Thus each species had the same internal efficiency of P use curve, and yields varied only with P concentration in tissue.Bicarbonate-extractable soil P was determined on soil samples taken in mid-July of 1989 and 1990. These soil test values were related to grain yields at harvest. The relationship between yield and soil test values had the same general form but varied for different species within years and for each species between years. It also varied for each species within years depending on the year the P was applied.     

Comparison of the Pi,Colwell, Bray 1, calcium acetate lactate (CAL) and Truog soil phosphorus test for predicting growth of oats,barley, triticale and clover in the field in lateritic soils fertilised with superphosphate and rock phosphate

The P_i soil test for phosphorus (P), which uses an iron oxide impregnated paper, was evaluated in three field experiment on lateritic soils in south-western Australia fertilised with triple superphosphate, North Carolina rock phosphate, Queensland rock phosphate, and in one experiment, Calciphos. Soil samples were collected February to March from 1985 to 1988. The P_i, Colwell, Bray 1, calcium acetate lactate (CAL) and Truog soil P tests were used. Soil test P values were related to yields of triticale (×Triticosecale) or oats (Avena sativa), barley (Hordeum vulgare) or dry herbage yields of subterranean clover (Trifolium subterraneum). The Colwell soil test, which is commonly used in Australia, and the Pi soil test were almost equally predictive, but showed considerable error in prediction of yield. For each soil test and plant species the relationship between yield and soil test P differed with fertilizer type and year. For combined data for all sites, fertilizers and years, the CAL soil test was the most predictive and the Truog soil test was least predictive of plant yield.     

A comparison of five soil phosphorus tests for five crop species for soil previously fertilized with superphosphate and rock phosphate

The P_i, Colwell, Bray 1, calcium acetate lactate (CAL) and Truog phosphorus (P) soil test reagents were assessed in two field experiments on lateritic soils in Western Australia that had been fertilized four years previously (1984) with triple superphosphate, North Carolina rock phosphate, Queensland rock phosphate, and in one experiment, Calciphos. Soil samples to measure soil P test were collected February 1987. Soil P test was related to seed (grain) yields measured later in 1987. Different crop species were grown on different sections of the same plot at each site. The species were lupins (Lupinus angustifolius), barley (Hordeum vulgare) and oats (Avena sativa) at one site, and lupins, oats, triticale (×Triticosecale) and rapeseed (Brassica napus) at the other site. For each reagent, the soil P test calibration, which is the relationship between yield, expressed as a percentage of the maximum yield, and soil P test, generally differed for different plant species and for different fertilizer types. Variations in soil P test required to produce half the maximum yield of each species at each site was least for the CAL reagent followed by the Colwell reagent.     

The influence of seasonal conditions,plant species and fertilizer type on the prediction of plant yield using the Colwell bicarbonate soil test for phosphate

Testing for soil phosphate (P) using the Colwell procedure is widely used in south-western Australia to estimate fertilizer applications required for crops and pastures. The relationship between plant yield, expressed as a percentage of the maximum yield, and soil test values is assumed to be constant in different years for the same soil type and plant species. Data from 11 long-term field experiments in south-western Australia show that regardless of whether percentage of maximum or absolute yield is used, the relationship between yield and soil test values is different (1)in different years, for the same site and where the same P fertilizer type has been used. This occurred irrespective of whether the same or different plant species were grown in different years; (2)where different types of P fertilizer had been used, for the same site, same year and same plant species; (3)for different plant species, for the same site, same year, and same type of P fertilizer. We conclude that considerable errors in the recommendation of fertilizer rates may result from the assumption that there is a constant relationship between soil test and yield.     

Effects of phosphorus on yield of cowpea cultivars intercropped with pearl millet on Psammentic paleustalf in Niger

Phosphorus (P) is the most limiting soil nutrient in the sandy soils of Niger and farmers rarely use chemical fertilizers in producing pearl millet and cowpea. A 3-yr study was conducted in farmer's fields at two locations in South Western Niger to investigate yield response of six cowpea cultivars to applied P-fertilizer (0, 8, 16 kg ha^–1) when intercropped with millet. Significant yield differences were found between cultivars for their seed and dry fodder yield at all rates of applied P. Cultivars responded differently to the application of P. Millet grain was more than doubled with the addition of 8 to 16 kg P ha^–1. Cowpea cultivars did not have significant differential effect on millet yields. Cowpea cultivars differed significantly in the accumulation of P in fodder with the highest yielding cultivars taking up more P than the low yielding ones. The results have important implications for breeding and selection of cowpea cultivars that are adapted to a range of fertility levels.Submitted as Journal Article No. 1211 of ICRISAT.     

Penicillium bilaji and phosphorus fertilization effects on the growth,development, yield and common root rot severity of spring wheat

A strain ofPenicillium bilaji Chalabuda (PB) has recently been commercially released as a seed inoculant to increase phosphorus (P) uptake by wheat (Triticum aestivum L.). The purpose of this study was to compare the effects of drill applied P (15 kg P ha^–1) with PB seed inoculation on early growth, development, P uptake, and grain yield of Stoa spring wheat at four sites in North Dakota.Fertilization with P consistently enhanced early season growth, main stem development, tillering and P uptake. Seed inoculation with PB had little or no effect on these traits. Phosphorus fertilization tended to increase common root rot severity (CRR, incited byCochliobolus sativus (Ito & Kurib) Drechs.), while PB inoculation had no effect. Grain yields were significantly increased by P fertilization at one location. Inoculation with PB also increased grain yield at this location. The reason why PB inoculation increased yield at this location is not evident, as plant growth and P uptake were not enhanced earlier in the season. Averaged across all four sites, PB inoculation increased wheat yields 66 kg ha^–1, which is similar to averaged yield responses reported from the Prairie Provinces of Canada.     

Comparison of single and coastal superphosphate for subterranean clover on phosphorus leaching soils

Coastal superphosphate, a partially acidulated rock phosphate (PARP), is being considered as an alternative fertilizer to single superphosphate for pastures in high rainfall (> 800 mm annual average) areas of south-western Australia. The effectiveness of single and coastal superphosphate, as P fertilizers, was measured in two field experiments using dry herbage yield of subterranean clover (Trifolium subterraneum). The experiments were started in April 1990 and were terminated at the end of 1993. In the years after P applications, soil samples were collected each January to measure Colwell soil-test P, which was related to plant yields measured later on that year, to provide soil P test calibrations.Relative to freshly-applied single superphosphate, the effectiveness of freshly-applied coastal superphosphate and the residues of previously-applied single and coastal superphosphate were less effective in some years (from 3% as effective to equally effective), and up to 100% more effective in other years. This large range in effectiveness values in different years is attributed to different climatic conditions. Soil P test calibrations were different for soils treated with single or coastal superphosphate. The calibrations were also different for different yield assessments (harvests) in the same year, and in different years. Consequently soil P testing can only provide a very crude estimate of the current P status of the soils.     

Residual value of superphosphate measured using yields of different pasture legume species and bicarbonate — extractable soil phosphorus

The residual value of superphosphate was measured in three glasshouse pot experiments using three different lateritic soils (pH CaCl₂: 4.8–5.3) from south-western Australia. The residual value was estimated relative to levels of freshly-applied superphosphate using yield of dried tops and bicarbonatesoluble P extracted from the soil (soil test values). Up to five successive crops were grown. In each experiment, four different pasture legume species fertilized with mineral nitrogen were grown in rotation with a cereal species. The legume species includedMedicago polymorpha, M. murex, Trifolium subterraneum, Ornithopus compressus, O. perpusillus andO. pinnatus. The cereal species includedTriticum aestivum, ×Triticosecale, andHordeum vulgare. The comparative phosphorus (P) requirement of the different pasture legumes was estimated from the amount of P required to produce 50 or 90% of the maximum yield measured for each species at each harvest. Soil samples for the soil test were collected just before sowing each crop, and were related to the plant yields of that crop.Relative to freshly-applied superphosphate, the residual value of superphosphate measured using plant yield was similar for all pasture legume species, and decreased markedly, by about 50 to 80% between the first and second crop, and by a further 5 to 30% for subsequent crops. The decrease in residual value estimated using soil test values was less marked. For freshly-applied superphosphate, and for the same plant species, the relationship between yield and the level of P applied differed for different crops.There was no consistent, systematic trend for the comparative P requirement of the different legume species within and between crops of the three experiments and soils.For all crops, the relationship between yield of dried tops and P concentration in dried tissue generally differed for the different legume species, indicating the different species usually have different internal efficiency of P use curves. However, for each experiment, when the same cereal species was grown in all the pots, the relationship between yield and P concentration in tissue was similar for previously- and freshly-applied superphosphate, regardless of the pasture legume species grown in previous crops.The relationship between yield and soil test values usually differed, within each crop, for different plant species and for previously- and freshly-applied superphosphate. For the same plant species, the relationship also differed between different crops.     

Associations between Oil Yield and Profile of Fatty Acids,Sterols, Squalene,Carotenoids, and Tocopherols in Seed Oil of Selected Japanese Quince Genotypes during Fruit Development

Tocopherols, phytosterols, carotenoids, and squalene are present in mature seeds of Japanese quince. Yet, little is known about the relationship between these compounds and oil yield during fruit and seed development. The profile change of lipophilic compounds during fruit and seed development in Japanese quince cultivars “Darius,” “Rondo,” and “Rasa” is investigated. It is shown here that during fruit and seed development, there is a significant reduction, three‐ to over tenfold, in the concentration of minor bioactive compounds in seed oil. It is recorded that delay between synthesis of tocopherols and oil in Japanese quince seeds during the fruit development results in a logarithmic relationship between the oil content and tocopherols concentration in the seed oil (R² = 0.980). Similar trends are observed between oil yield and phytosterols, and carotenoids (R² = 0.927 and R² = 0.959, respectively). The profile of fatty acids during the development of the seeds significantly is changed. The reduction of linoleic, palmitic, and gondoic acids levels and increment of oleic acid is noted. The oil content, profile of fatty acids, and concentration of bioactive compounds in all three genotypes of Japanese quince do not change significantly statistically during the last month of fruit development. Practical Applications: Some fruits are harvested at different degrees of maturity mainly due to a logistic issue and uneven ripening of fruits, which affects the chemical composition of whole fruit including seeds. Therefore, it would be good to know how the chemical composition is changing in plant material during development especially in the last month before harvest. Production of Japanese quince continues to rise year to year and with it the volume of generated by‐products such as seeds. This study demonstrates how it changes the oil content, profile of fatty acid, and concentration of tocopherols, squalene, phytosterols, and carotenoids in the seeds and seed oil of three Japanese quince cultivars “Rondo,” “Darius,” and “Rasa” during plant development. The provided information can be very useful for the manufactories oriented on the processing of by‐products, mainly seeds, generated by other branches of industry, for instance, fruit‐processing.     

A comparison of triple superphosphate and Gafsa ground rock phosphate fertilisers as P-sources for grass-clover swards on a poorly-drained acid clay soil

Organic farming practice prohibits the use of triple superphosphate (TSP) as a source of phosphorus. As basic slag is not now generally available, interest is focused on the relative value of ground rock phosphate (GRP). A comparison of TSP and Gafsa GRP was made during 1988–92 as to their ability to increase DM production under cutting from newly sown grass/white clover swards established in 1987 on an acid clay soil in SW England. Averaged over the different P fertiliser inputs and years, the DM yield was 8.0 t ha-1 y-1 (range 6.93–9.81) compared to 6.3t ha-1y-1 (range 6.00–7.71) without added P. Lime was added at either 3 or 6t ha-1 in 1987, and at half these rates in 1990. Whereas the yield improved by 45% with P at the lower rate of lime, it improved only by 12% at the higher rate. When P fertiliser was applied annually at 30 kg ha-1, TSP was superior to GRP, but when applied in one initial dose of 120 kg ha-1, GRP was superior over the subsequent 4 year period. There was no consistent effect of the addition of either P or lime on the clover content of the sward. The alkaline bicarbonate soil test (Olsen P) was a good predictor of available P within a given year; there was a general reduction of P availability over the course of the experiment. Mechanisms to explain the longer term effectiveness of GRP are postulated and discussed. It is concluded that farmers who are limited to using GRP rather than TSP would suffer a yield penalty over the longer term of 11.5%, and that P fertilizer for the ley phase in a rotation should be incorporated in one dose at the outset.     

Nitrogen fixation of red clover interseeded with winter cereals across a management-induced fertility gradient

The incorporation of legume cover crops into annual grain rotations remains limited, despite extensive evidence that they can reduce negative environmental impacts of agroecosystems while maintaining crop yields. Diversified grain rotations that include a winter cereal have a unique niche for interseeding cover crops. To understand how management-driven soil fertility differences and inter-seeding with grains influenced red clover (Trifolium pratense) N₂ fixation, we estimated biological N₂ fixation (BNF) in 2006 and 2007, using the ¹⁵N natural abundance method across 15 farm fields characterized based on the reliance on BNF derived N inputs as a fraction of total N inputs. Plant treatments included winter grain with and without interseeded red clover, monoculture clover, monoculture orchardgrass (Dactylis glomerata), and clover-orchardgrass mixtures. Fields with a history of legume-based management had larger labile soil nitrogen pools and lower soil P levels. Orchardgrass biomass was positively correlated with the management-induced N fertility gradient, but we did not detect any relationship between soil N availability and clover N₂ fixation. Interseeding clover with a winter cereal did not alter winter grain yield, however, clover production was lower during the establishment year when interseeded with taller winter grain varieties, most likely due to competition for light. Interseeding clover increased the % N from fixation relative to the monoculture clover (72% vs. 63%, respectively) and the average total N₂ fixed at the end of the first growing season (57 vs. 47 kg N ha⁻¹, respectively). Similar principles could be applied to develop more cash crop-cover crop complementary pairings that provide both an annual grain harvest and legume cover crop benefits.