Effects of Supplementary Soil Nutrients on Hummock Grasses

1994 ◽  
Vol 42 (6) ◽  
pp. 687 ◽  
Author(s):  
BL Rice ◽  
M Westoby ◽  
GF Griffin ◽  
MH Friedel
Keyword(s):  
Soil Nutrients ◽  
Total Phosphorus ◽  
Soil Phosphorus ◽  
Nitrogen Concentration ◽  
Nutrient Content ◽  
Separate Experiment ◽  
Phosphorus Concentration ◽  
Absolute Amount ◽  
Available Soil Phosphorus ◽  
Fertiliser Application

Hummocks of Triodia basedowii E. Pritz, T. pungens R.Br. and Plectrachne schinzii Henr. were treated with ash and with standard and high applications of slow-release fertiliser. Following rain and the ensuing growth and flowering, the soils and the hummocks were sampled for biomass and for nutrient content, and compared to controls. In a similar but separate experiment, seed set in inflorescences was assessed for hummocks treated with standard fertiliser application, for hummocks treated by removal of neighbouring hummocks, and for controls. In the absence of nutrient addition, total topsoil nitrogen concentration was higher under hummocks than outside, whereas total topsoil phosphorus concentration was lower under hummocks than outside. The absolute amount of phosphorus in the hummock itself was insufficient to account for the depletion of phosphorus in topsoil under the hummock. Available soil phosphorus was about 1-4% of total phosphorus, and was generally highest towards the edge of hummocks. Additions of ash did not significantly affect soil nutrients, while addition of fertiliser produced substantial increases in total nitrogen and in available and total phosphorus. The increases did not extend to the area surrounding the hummock. The increases in soil nutrients did not result in significant increases in new green growth, or in inflorescence biomass or number. However, nutrients appear to have been taken up into the plants, including into old tissue, because there were increases in nutrient concentration in plant tissues, which sometimes were statistically significant and sometimes not. In the second experiment, neither increased soil nutrients nor removal of neighbours increased the number of inflorescences produced, or the proportion of florets that gave rise to filled grain.

scholarly journals Effects of Cowpea-Amaranth Intercropping and Fertiliser Application on Soil Phosphatase Activities, Available Soil Phosphorus, and Crop Growth Response

Agronomy ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 79 ◽  
Author(s):  
Buhlebelive Mndzebele ◽  
Bhekumthetho Ncube ◽  
Melake Fessehazion ◽  
Tafadzwanashe Mabhaudhi ◽  
Stephen Amoo ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Crop Production ◽  
Soil Phosphorus ◽  
Phosphorus Concentration ◽  
Acid And Alkaline Phosphatase ◽  
Available Soil Phosphorus ◽  
Fertiliser Application ◽  
Inorganic Fertilisers

Low available soil phosphorus (P) is associated with its immobility, which renders it unavailable for plant uptake. In addition, farmers normally apply inorganic fertilisers to legumes to activate soil-bound phosphorus using root exudates. Sufficient soil mineral nutrition is key to sustainable crop production, and hence food and nutritional security. The aim of this study was to quantify the acid and alkaline phosphatase activity as an indicator of P supply and availability under varying levels of nitrogen, phosphorus and potassium (NPK) fertilization and different cropping systems. An intercropping (cowpea and amaranth) and fertiliser (control, 25%, 50%, and 100% of the recommended NPK levels) field trial was laid out in a 2 × 4 factorial treatment structure in a completely randomized design (CRD) with four replications. There was higher acid and alkaline phosphatase activity in the rhizosphere of cowpea and amaranth grown as sole crops compared to those from intercropping. The cowpea and amaranth plants grown without fertiliser or 25% NPK had the highest rhizospheric phosphatase activity, while 100% NPK application exhibited the least. The markedly higher phosphatase activity from the low fertiliser application treatments indicates the possible stimulation of microbial activity to supplement P demands for the crops. The study revealed that the application of lower rates inorganic fertilisers in a legume intercrop stimulates the activity of the phosphatase enzymes, which can subsequently liberate soil-bound phosphorus. Plant tissue phosphorus concentration of cowpea and amaranth plants increased proportionately to the increase in fertiliser application up to 50% of the recommended NPK level. The land equivalent ratio (LER) was greater than 1, indicating that it is more beneficial to intercrop cowpea and amaranth as opposed to growing them as sole crops. Overall, the application of NPK fertilizer to amounts of up to 50%, based on the results of this study, appear to be better than 100% in terms of biomass accumulation and phosphate activity.

Lake Paranoá, Brasília, Brazil: Integrated Management Plan for its Restoration

1992 ◽  
Vol 27 (2) ◽  
pp. 271-286 ◽  
Author(s):  
Sonia Paulino Mattos ◽  
Irene Guimarães Altafin ◽  
Hélio José de Freitas ◽  
Cristine Gobbato Brandão Cavalcanti ◽  
Vera Regina Estuqui Alves
Keyword(s):  
Total Phosphorus ◽  
Drainage Basin ◽  
Integrated Management ◽  
Algal Growth ◽  
Nutrient Content ◽  
Management Plan ◽  
Cylindrospermopsis Raciborskii ◽  
Phosphorus Concentration ◽  
Limiting Factor ◽  
Total Phosphorus Concentration

Abstract Built in 1959, Lake Paranoá, in Brasilia, Brazil, has been undergoing an accelerated process of nutrient enrichment, due to inputs of inadequately treated raw sewage, generated by a population of 600,000 inhabitants. Consequently, it shows high nutrient content (40 µg/L of total phosphorus and 1800 µg/L of total nitrogen), low transparency (0.65 m) and high levels of chlorophyll a (65 µg/L), represented mainly by Cylindrospermopsis raciborskii and sporadic bloom of Microcystis aeruginosa, which is being combatted with copper sulphate. With the absence of seasonality and a vertical distribution which is not very evident, the horizontal pattern assumes great importance in this reservoir, in which five compartments stand out. Based on this segmentation and on the identification of the total phosphorus parameter as the limiting factor for algal growth, mathematical models were developed which demonstrate the need for advanced treatment of all the sewage produced in its drainage basin. With this, it is expected that a process of restoration will be initiated, with a decline in total phosphorus concentration to readings below 25 µg/L. Additional measures are proposed to accelerate this process.

scholarly journals Reducing Nitrogen and Phosphorus Losses from Different Crop Types in the Water Source Area of the Danjiang River, China

2019 ◽  
Vol 16 (18) ◽  
pp. 3442 ◽  
Author(s):  
Mengjing Guo ◽  
Tiegang Zhang ◽  
Jing Li ◽  
Zhanbin Li ◽  
Guoce Xu ◽  
...  
Keyword(s):  
Total Nitrogen ◽  
Total Phosphorus ◽  
Unit Area ◽  
Nitrogen Concentration ◽  
Source Area ◽  
Water Source ◽  
Nutrient Loss ◽  
Phosphorus Concentration ◽  
Nitrogen And Phosphorus ◽  
Bare Land

Nitrogen and phosphorus are essential for plant growth and are the primary limiting nutrient elements. The loss of nitrogen and phosphorus in agricultural systems can cause the eutrophication of natural water bodies. In this paper, a field simulated rainfall experiment was conducted in a typical small watershed of the Danjiang River to study the nutrient loss process of nitrogen and phosphorus in slope croplands subjected to different crops and tillage measures. The characteristics of the runoff process and nutrient migration of different slope treatments were studied, which were the bare-land (BL, as the control), peanut monoculture (PL), corn monoculture (CL), bare land (upper slope) mixed with peanut monoculture (lower slope) (BP), corn and peanut intercropping (TCP), corn and soybean intercropping (TCS), downslope ridge cultivation (BS) slope, and straw-mulched (SC), respectively. The results showed that the runoff of CL, SC, TCS, BS, BP, PL and TCP slope types were 93%, 75%, 51%, 39%, 28%, 12%, and 6% of the those of the bare land, respectively. The total nitrogen concentration in runoff on different slope types decreased in the order of BP > PL > BS > SC > TCP > BL > CL > TCS. The BL was characterized with the highest NRL-TN (the loss of total nitrogen per unit area), with the value of 1.188 kg/hm2, while those of the TCP is the smallest with the value of 0.073 kg/hm2. The total phosphorus concentration in runoff decreasd in the order of BS > BP > PL > BL > TCP > SC > CL > TCS. The PRL-TP (the loss of total phosphorus per unit area) of BL is the largest (0.016 kg/hm2), while those of TCP is the smallest (0.001 kg/hm2). These indicate that the loss of nitrogen is much higer than that of phosphorus. The loss of nitrogen in runoff is dominated by nitrate nitrogen, which accounts for 54.4%–78.9% of TN. Slope croplands in the water source area should adopt the tillage measures of TCP and PL.These measures can reduce 85% of the runoff of nitrogen and phosphorus compared to the bare land. The results may assist in agricultural non-point source pollution control and help promote improved management of the water environment in the Danjiang River’s water source area.

scholarly journals A novel submerged Rotala rotundifolia, its growth characteristics and remediation potential for eutrophic waters

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Chaoguang Gu ◽  
Feifei Li ◽  
Jibo Xiao ◽  
Shuyi Chu ◽  
Shuang Song ◽  
...  
Keyword(s):  
Total Phosphorus ◽  
Nitrogen Concentration ◽  
Biomass Accumulation ◽  
Ammonium Nitrogen ◽  
Phosphorus Concentration ◽  
Nitrogen And Phosphorus ◽  
Overlying Water ◽  
Total Phosphorus Concentration ◽  
Submerged Aquatic Plant ◽  
Nitrogen Contents

Abstract The vegetative growth and remediation potential of Rotala rotundifolia, a novel submerged aquatic plant, for eutrophic waters were investigated on different sediments, and under a range of nitrogen concentrations. Rotala Rotundifolia grew better on silt than on sand and gravel in terms of plant height, tiller number and biomass accumulation. Percent increment of biomass was enhanced at low water nitrogen (ammonium nitrogen concentration ≤10 mg/L). The maximum total nitrogen and total phosphorus removals in the overlying water were between 54% to 66% and 42% to 57%, respectively. Nitrogen contents in the sediments increased with increasing water nitrogen levels, whereas, nitrogen contents in the plant tissues showed no apparent regularity, and the greatest value was obtained at ammonium nitrogen concentration 15 mg/L. Both phosphorus contents in the sediments and tissues of plants were not affected significantly by additional nitrogen supply. Direct nitrogen uptake by plants was in the range of 16% to 39% when total phosphorus concentration was 1.0 mg/L. These results suggested that Rotala Rotundifolia can be used to effectively remove nitrogen and phosphorus in eutrophic waters.

Improvements in Quantifying the Phosphorus Concentration in Lake Water

1982 ◽  
Vol 39 (6) ◽  
pp. 822-829 ◽  
Author(s):  
E. E. Prepas ◽  
F. H. Rigler
Keyword(s):  
Particulate Matter ◽  
Water Column ◽  
Total Phosphorus ◽  
Lake Water ◽  
Separate Experiment ◽  
Phosphorus Concentration ◽  
Water Bottle ◽  
Acid Digestion ◽  
Average Variance ◽  
The Mean

Vertical and horizontal patterns in limnetic phosphorus concentrations ([P]) were detected in an oligotrophic lake by dividing the total phosphorus pool into two fractions: dissolved and particulate matter smaller than 250 μm (smaller fraction) and particulate matter larger than 250 μm (larger fraction). The smaller fraction was estimated from samples collected with a water bottle, and the larger fraction was estimated with tow net samples taken at several stations and to various depths. Our samples were digested with potassium persulfate which gave less variable results than other acid digestion techniques. The average variance associated with the mean [P] (n = 3) for samples collected and analyzed according to our procedure was less than 0.05 mg P/m3. During summer stratification there was a consistent metalimnetic maximum in the smaller fraction, and there were small but significant differences in the concentrations found at two stations less than 1 km apart. During the same period the larger fraction was a significant portion (14–28%) of the phosphorus pool in the epilimnion which varied from 3 to 5 m in depth. It was a relatively constant portion of the phosphorus in the trophogenic zone (0–10 m) and in the 0- to 20-m portion of the water column i.e. 10–14% and 7.3–8.8%, respectively. In a separate experiment it was shown that by removing the larger fraction, the average variance associated with the mean [P] was reduced from 1.0, to 2.4 × 10−2 mg/m3. This reduction occurred because the larger fraction contained zooplankters with relatively high but variable amounts of phosphorus, and which occur in densities too low to be adequately sampled with the smaller fraction.Key words: phorphorus, lakes, phosphorus in zooplankton

Nutrition of irrigated crops on an alkaline brown clay soil at Trangie, New South Wales. 1. Lucerne

1986 ◽  
Vol 26 (4) ◽  
pp. 445
Author(s):  
DK Muldoon
Keyword(s):  
Dry Matter ◽  
Soil Phosphorus ◽  
Dry Matter Production ◽  
Yield Response ◽  
Phosphorus Concentration ◽  
Alkaline Soil ◽  
Phosphorus Level ◽  
South Wales ◽  
Matter Production ◽  
Available Soil Phosphorus

The elements nitrogen, phosphorus, potassium, sulfur and zinc were sequentially omitted from a 'complete' fertiliser applied to plots on an alkaline soil, and lucerne (Medicago sativa) was sown immediately afterwards. The dry matter production of lucerne was measured in repeated cuts over 2 years; its mineral composition was determined periodically. In a second experiment 4 rates of phosphorus were applied to a l -year-old stand of lucerne and dry matter production recorded for 1 year. Lucerne yields in the first year were reduced from 17-1 8 t/ha to less than 14 t/ha by omitting phosphorus. Yields universally decreased in the second year as the 50 kg/ha P applied at sowing was depleted through the removal of 40 kg/ha P in forage. Following this depletion a linear yield response up to 80 kg/ha P was found (experiment 2). Omitting phosphorus fertiliser reduced the plant phosphorus concentration from 0.23 to 0.21% when sampled 15 months after sowing. The plant phosphorus concentration decreased with time in all treatments. The available soil phosphorus level decreased from an initial 12 to 6-7 �g/g after 6 months and further to 2 �g/g after 30 months. Fertiliser phosphorus raised the soil phosphorus level but this also was depleted to 2-3 �g/g in 30 months. Omitting zinc reduced the plant zinc concentration. However, neither the omission of nitrogen, potassium, sulfur nor zinc from the fertiliser had any effect on lucerne yields.

Seasonal changes in chemical composition of heavily fertilized Kikuyu pasture and their potential effects on the mineral nutrition of grazing cattle

1979 ◽  
Vol 19 (97) ◽  
pp. 183 ◽  
Author(s):  
AS Awad ◽  
DG Edwards ◽  
DO Huett
Keyword(s):  
Nitrogen Concentration ◽  
Nutrient Content ◽  
Early Summer ◽  
Phosphorus Concentration ◽  
Late Winter ◽  
Grazing Cattle ◽  
Nitrogen Concentrations ◽  
One Year ◽  
High Level ◽  
Phosphorus Application

was sampled at two week intervals over a period of one year. The concentrations of calcium throughout the year (0.15-0.28%) and phosphorus from late winter to early summer (0.20-0.28%) were well below the values normally considered to be required by milking cows and some classes of beef cattle. The nitrogen concentrations reached minimal values of 1.8-2.2% in winter, which appear to be adequate for milk production. From summer through to the end of winter, the ratio of K/(Ca + Mg) was much higher, and the Ca/P ratio was much lower, than those values reported to be associated with the occurrence of grass tetany in grazing cattle. Very high nitrogen concentratians in early summer (up to 5.2% N where 672 kg N ha-1 year-1 was applied) were in the range that has been associated with grass tetany in cattle. Lime application increased the nitrogen, phosphorus and calcium concentrations in the herbage throughout the year. The effect of lime in increasing nitrogen concentration in the herbage was maximal in late autumn and winter, at which time fertilizer nitrogen had little or no effect. The increased nitrogen concentration in the herbage through application of lime was associated with the development of a naturalized white clover component in the sward. Lime also increased the phosphorus concentration in the herbage, particularly from mid-winter to early summer, over which period phosphorus application per se had minimal effect. The application of lime allied with 134 kg N ha-1 year-1 maintained a high level of dry matter production as well as a more adequate and better balanced nutrient content in the kikuyu pasture throughout the year, and particularly in winter, when cattle grazing kikuyu pastures suffer a serious feed gap.

The effects of organic and inorganic phosphorus concentration on the acid phosphatase activity of ectomycorrhizal fungi

1988 ◽  
Vol 66 (4) ◽  
pp. 750-756 ◽  
Author(s):  
Carolyn J. Kroehler ◽  
Robert K. Antibus ◽  
Arthur E. Linkins
Keyword(s):  
Phosphatase Activity ◽  
Ectomycorrhizal Fungi ◽  
Organic Phosphorus ◽  
Soil Phosphorus ◽  
Axenic Culture ◽  
Inorganic Phosphorus ◽  
Phosphorus Concentration ◽  
Cenococcum Geophilum ◽  
Available Soil Phosphorus ◽  
Substrate Hydrolysis

Kinetic constants (Km and Vmax) were determined for surface and extracellular soluble acid phosphatases produced by two ectomycorrhizal fungi (Cenococcum geophilum Fr. and Entoloma sericeum (Bull, ex Merat) Quel.) grown in axenic culture at 2 or 50 μM KH2PO4 or sodium inositol hexaphosphate. Results for cultures supplied inorganic phosphorus were similar to those supplied organic phosphorus: surface Vmax estimates were significantly greater for 2 than for 50 μM grown isolates. The presence of constitutive extracellular soluble phosphatase activity resulted in the appearance of inorganic phosphate in media initially supplied with organic phosphorus, suggesting substrate hydrolysis in excess of phosphate uptake. No consistent relationship was found between apparent Km estimates and phosphorus treatments. The two species had surface phosphatase Vmax values differing by as much as two orders of magnitude. The magnitude of the response to phosphorus treatment differed among isolates. The response of phosphatases to changes in phosphorus at concentrations comparable with soil solution phosphorus supports the hypothesis that levels of available soil phosphorus may control ectomycorrhizal phosphatase production or activation.

Response of summer chlorophyll concentration to reduced total phosphorus concentration in the Rhine River (Netherlands) and the Sacramento – San Joaquin Delta (California, USA)

2007 ◽  
Vol 64 (11) ◽  
pp. 1529-1542 ◽  
Author(s):  
Erwin E Van Nieuwenhuyse
Keyword(s):  
Total Phosphorus ◽  
Nitrogen Concentration ◽  
Chlorophyll Concentration ◽  
Water Systems ◽  
Phosphorus Loading ◽  
Phosphorus Concentration ◽  
Flowing Water ◽  
Rhine River ◽  
Total Phosphorus Concentration ◽  
Fold Reduction

Reductions in wastewater loading led to significant declines in mean summer total phosphorus (TP) and chlorophyll concentration (Chl) in two large flowing water systems despite their initially shallow (<2 m) euphotic depth and continually high (>40 mg·m-3) soluble reactive P concentration. In the Rhine River, a gradual 2.7-fold reduction in TP resulted in a 4-fold decline in Chl. In the Sacramento – San Joaquin Delta, an abrupt 1.5-fold reduction in TP led to an equally abrupt 2.6-fold reduction in Chl. Neither response could be attributed to coincidental changes in flow, light, or nitrogen concentration. The slope of the response (Chl:TP) in both systems paralleled the average trajectory calculated using an among-system TP–Chl relationship for a broad cross section of flowing waters. The results suggest that TP was the principal determinant of Chl in both systems and that control of phosphorus loading may be an effective tool for managing eutrophication in other flowing water systems with relatively high (10–100 mg·m-3) soluble reactive P concentrations.

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