Root distributions of Australian herbaceous perennial legumes in response to phosphorus placement

2006 ◽  
Vol 33 (12) ◽  
pp. 1091 ◽  
Author(s):  
Matthew D. Denton ◽  
Camille Sasse ◽  
Mark Tibbett ◽  
Megan H. Ryan

Many Australian plant species have specific root adaptations for growth in phosphorus-impoverished soils, and are often sensitive to high external P concentrations. The growth responses of native Australian legumes in agricultural soils with elevated P availability in the surface horizons are unknown. The aim of these experiments was to test the hypothesis that increased P concentration in surface soil would reduce root proliferation at depth in native legumes. The effect of P placement on root distribution was assessed for two Australian legumes, Kennedia prorepens F. Muell. and Lotus australis Andrews, and the exotic Medicago sativa L. Three treatments were established in a low-P loam soil: amendment of 0.15 g mono-calcium phosphate in either (i) the top 50 mm (120 µg P g–1) or (ii) the top 500 mm (12 µg P g–1) of soil, and an unamended control. In the unamended soil M. sativa was shallow rooted, with 58% of the root length of in the top 50 mm. K. prorepens and L. australis had a more even distribution down the pot length, with only 4 and 22% of their roots in the 0–50 mm pot section, respectively. When exposed to amendment of P in the top 50 mm, root length in the top 50 mm increased 4-fold for K. prorepens and 10-fold for M. sativa, although the pattern of root distribution did not change for M. sativa. L. australis was relatively unresponsive to P additions and had an even distribution of roots down the pot. Shoot P concentrations differed according to species but not treatment (K. prorepens 2.1 mg g–1, L. australis 2.4 mg g–1, M. sativa 3.2 mg g–1). Total shoot P content was higher for K. prorepens than for the other species in all treatments. In a second experiment, mono-ester phosphatases were analysed from 1-mm slices of soil collected directly adjacent to the rhizosphere. All species exuded phosphatases into the rhizosphere, but addition of P to soil reduced phosphatase activity only for K. prorepens. Overall, high P concentration in the surface soil altered root distribution, but did not reduce root proliferation at depth. Furthermore, the Australian herbaceous perennial legumes had root distributions that enhanced P acquisition from low-P soils.

1992 ◽  
Vol 43 (1) ◽  
pp. 19 ◽  
Author(s):  
KY Chan ◽  
JA Mead

Root growth and distribution of wheat under different tillage practices was studied in a 4-year-old tillage experimental site at Cowra, N.S.W. Tillage affected root density as well as distribution. Up to 98 days after sowing, root length density was lower (P < 0.05) in the 0.05-0.10 m layer of the direct-drilled soil than the conventionally cultivated soil. Poor root growth found in direct-drilled soils, which was significantly related to the poor shoot growth, was not caused by soil physical conditions, viz. higher bulk density and soil strength. Rather, biological factors were involved because fumigation completely eliminated the poor shoot growth and significantly increased root length density of the direct drilled soils. Compared to a compaction treatment, roots grown under direct drilling, in addition to having lower density, also had impaired function. Under conventional cultivation, significantly lower root length density was found in the surface soil layer (0-0.05 m) and maximum root length density was found in the 0-05-0.10 m layer. Fumigation did not change the root distribution pattern. This tillage-induced difference in root distribution reflected less favourable surface soil conditions as a result of cultivation, e.g. seedbed slumping, compared to the soil under direct drilling.


1993 ◽  
Vol 70 (1) ◽  
pp. 249-268 ◽  
Author(s):  
P. P. Ketaren ◽  
E. S. Batterham ◽  
E. White ◽  
D. J. Farrell ◽  
B. K. Milthorpe

Two experiments were conducted to determine the available P requirements of grower and grower/finisher pigs and to define the conditions for conducting a growth assay for P availability. In the first experiment, diets with four levels of calculated available P (1–4 g/kg) and four Ca: available P ratios (1·7–2·9) were used to determine the available P requirements of grower pigs. The diets were formulated by substituting the required amounts of limestone and sodium tripolyphosphate for sugar in a soya-bean meal and sugar-based diet. In addition to measuring growth responses, a range of bones were examined to determine the most suitable criteria for assessing the response to available P. There was a small quadratic response of feed intake and growth rate of the pigs to level of available P, with maximum responses occurring to approximately 3 g available P/kg (P < 0·05). There were linear depressing effects of increasing Ca:available P ratios on carcass gain and feed conversion ratio (P < 0·01) but most of these effects occurred when the ratio exceeded 2·5:1. All bone variables examined increased linearly (P < 0·05) or curvilinearly (P < 0·01) with increasing available P concentration. In general, these variables were not affected by the Ca: available P ratio. The results of the growth responses and bone development indicate that the grower pig requires approximately 3 g available P/kg. However, for availability assays, where linearity of response is needed, the dietary concentration of available P should be a maximum of approximately 2 g/kg. In the second experiment four levels of calculated available P (1–4 g/kg) with a Ca: available P ratio of 2·5:1 were used to determine the available P requirements of grower/finisher pigs from 20 to 90 kg live weight. At 50 kg live weight the dietary available P concentration for half the pigs fed at 2, 3 and 4 g available P/kg was reduced to 1, 2 and 3 g/kg respectively. The pigs were fed ad lib. and growth performance, bone characteristics, P retention and ash concentration in the empty body were taken as response criteria to assess P adequacy. Among the variables tested, the ash concentration in the radius/ulna bone and P and ash concentrations in the empty body appeared to be more responsive than other variables to the changes in dietary P levels. Based on these variables, the P requirements for growth and bone development of growing pigs from 20 to 50 kg live weight was 3 g/kg and reduced to 2 g/kg for finisher pigs from 50 to 90 kg live weight.


2021 ◽  
Author(s):  
Xiucheng Liu ◽  
Yuting Wang ◽  
Shuangri Liu ◽  
Miao Liu

Abstract Aims Phosphorus (P) availability and efficiency are especially important for plant growth and productivity. However, the sex-specific P acquisition and utilization strategies of dioecious plant species under different N forms are not clear. Methods This study investigated the responsive mechanisms of dioecious Populus cathayana females and males based on P uptake and allocation to soil P supply under N deficiency, nitrate (NO3 −) and ammonium (NH4 +) supply. Important Findings Females had a greater biomass, root length density (RLD), specific root length (SRL) and shoot P concentration than males under normal P availability with two N supplies. NH4 + supply led to higher total root length, RLD and SRL but lower root tip number than NO3 − supply under normal P supply. Under P deficiency, males showed a smaller root system but greater photosynthetic P availability and higher leaf P remobilization, exhibiting a better capacity to adaptation to P-deficiency than females. Under P deficiency, NO3 − supply increased leaf photosynthesis and PUE but reduced RLD and SRL in females while males had higher leaf P redistribution and photosynthetic PUE than NH4 + supply. Females had a better potentiality to cope with P deficiency under NO3 − supply than NH4 + supply; the contrary was true for males. These results suggest that females may devote to increase in P uptake and shoot P allocation under normal P availability, especially under NO3 − supply, while males adopt more efficient resource use and P remobilization to maximum their tolerance to P-deficiency.


Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 708
Author(s):  
Phanthasin Khanthavong ◽  
Shin Yabuta ◽  
Hidetoshi Asai ◽  
Md. Amzad Hossain ◽  
Isao Akagi ◽  
...  

Flooding and drought are major causes of reductions in crop productivity. Root distribution indicates crop adaptation to water stress. Therefore, we aimed to identify crop roots response based on root distribution under various soil conditions. The root distribution of four crops—maize, millet, sorghum, and rice—was evaluated under continuous soil waterlogging (CSW), moderate soil moisture (MSM), and gradual soil drying (GSD) conditions. Roots extended largely to the shallow soil layer in CSW and grew longer to the deeper soil layer in GSD in maize and sorghum. GSD tended to promote the root and shoot biomass across soil moisture status regardless of the crop species. The change of specific root density in rice and millet was small compared with maize and sorghum between different soil moisture statuses. Crop response in shoot and root biomass to various soil moisture status was highest in maize and lowest in rice among the tested crops as per the regression coefficient. Thus, we describe different root distributions associated with crop plasticity, which signify root spread changes, depending on soil water conditions in different crop genotypes as well as root distributions that vary depending on crop adaptation from anaerobic to aerobic conditions.


2010 ◽  
Vol 36 (1) ◽  
pp. 11-17
Author(s):  
Karen Smith ◽  
Peter May ◽  
Robert White

Spotted gum (Corymbia maculata (Hook.) K.D. Hill & L.A.S. Johnson), a common street tree in southern Australian cities, was used to assess growth responses to variations in profile design and organic amendment of constructed soils. Aboveground growth responses were total stem dry weight and foliar nutrient content. The belowground response was root length density. Soil profiles were constructed of sand, amended with either coir fiber, composted biosolids or composted green waste, at rates of 0, 5, 10 or 20% by volume. The profiles were either layered, with a 150 mm (6 in) organic-amended surface layer, or uniform, with amendment of the entire profile. A single fertilizer treatment was applied to all profiles. Shoot dry weight was only affected by organic matter type with the greatest growth in sand amended with composted biosolids. Foliage P and K content were affected by amendment but foliage N was not. Profile design affected root length density and distribution. Trees in uniform profiles had greater root length density, and a more uniform distribution of roots, especially with compost amendments. Above- and belowground growth increases are thought to be due to increased nutrient status resulting from organic matter mineralization.


2000 ◽  
Vol 30 (1) ◽  
pp. 136-144 ◽  
Author(s):  
C A Raymond ◽  
A Muneri

The effects of N and P fertilizers applied to Eucalyptus globulus Labill. at plantation establishment on basic density, fibre length, fibre coarseness, predicted pulp yield, and N and P concentration in the wood were examined by sampling four fertilizer factorial trials: three in Victoria and one in Western Australia. Treatments sampled were control, maximum levels of N and P by themselves and combined. Growth responses varied across sites with significant growth responses at the Victorian sites but no response at the Western Australian site. An interaction was suggested between rainfall and the effects of the fertilizer; wood properties at the drier sites were detrimentally affected by fertilizer but there was little effect at the wetter sites. On the two drier sites, application of both N and P, alone or in combination, resulted in changes in density, shorter fibres, and slightly lower predicted pulp yield. Addition of both N and P increased the levels of these nutrients in the wood at the three Victorian sites. Changes occurred in wood properties in the absence of growth responses to the applied fertilizer indicating that these changes were not induced by changing tree growth rate.


2005 ◽  
Vol 85 (5) ◽  
pp. 589-597 ◽  
Author(s):  
Chi Chang, Joann K. Whalen ◽  
Xiying Hao

Migration of P from soils to water resources poses a risk of surface water eutrophication, and increase in P concentration in soils through manure or fertilizer addition would exace rbate this problem. Investigating the rate of increase in P concentration of surface soil receiving livestock manure is crucial to the development of best manure management strategies and prevention of eutrophication of aquatic systems. In this study, the changes in P concentrations of surface soils (0- to 15-cm depth) receiving 25 annual manure applications at rates of 0, 30, 60 and 90 Mg ha-1 yr-1 under non-irrigated conditions and at rates of 0, 60, 120 and 180 Mg ha-1 yr-1 under irrigated conditions were examined. The soil test P (STP) and total P (TP) of the surface soil increased with the TP through manure application over a 25-yr period. The STP pool was about 38% of the soil TP pool, similar to ratios of STP to TP in feedlot cattle manure. While the high proportion of STP to TP could be beneficial for crop production, it could also increase the potential for P losses from these soils through runoff and leaching. The changes in TP and STP concentrations of the surface soil were modelled with an expone ntial rise to maximum function: TP = 0.69 + 5.06 (1 − e(−0.087x)) and STP = 0.029 + 2.21 (1 − e(−0.082x)) where x is the cumulative TP applied. Although the model was developed for a specific soil and type of manure, it could be adapted to other soils or manure sources by adjusting the model coefficients for the particular soil and/or manure type. These adjustments would not require as extensive a data set as was required to develop the original model. This model could be used to determine the amount of TP that could be applied for a given critical STP. Producers, regulatory agencies, planners, and extension specialists could also use this model to make decisions on manure P management. Key words: Long-term cattle manure application, total phosphorus, available phosphorus, rate of accumulation, non-irrigated and irrigated cropping


2001 ◽  
Vol 5 (4) ◽  
pp. 629-644 ◽  
Author(s):  
M. T. van Wijk ◽  
W. Bouten

Abstract. In this modelling study differences in vertical root distributions measured in four contrasting forest locations in the Netherlands were investigated. Root distributions are seen as a reflection of the plant’s optimisation strategy, based on hydrological grounds. The "optimal" root distribution is defined as the one that maximises the water uptake from the root zone over a period of ten years. The optimal root distributions of four forest locations with completely different soil physical characteristics are calculated using the soil hydrological model SWIF. Two different model configurations for root interactions were tested: the standard model configuration in which one single root profile was used (SWIF-NC), and a model configuration in which two root profiles compete for the same available water (SWIF-C). The root profiles were parameterised with genetic algorithms. The fitness of a certain root profile was defined as the amount of water uptake over a simulation period of ten years. The root profiles of SWIF-C were optimised using an evolutionary game. The results showed clear differences in optimal root distributions between the various sites and also between the two model configurations. Optimisation with SWIF-C resulted in root profiles that were easier to interpret in terms of feasible biological strategies. Preferential water uptake in wetter soil regions was an important factor for interpretation of the simulated root distributions. As the optimised root profiles still showed differences with measured profiles, this analysis is presented, not as the final solution for explaining differences in root profiles of vegetation but as a first step using an optimisation theory to increase understanding of the root profiles of trees. Keywords: forest hydrology, optimisation, roots


Agronomy ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 310 ◽  
Author(s):  
Meng Kong ◽  
Jing Kang ◽  
Cheng-Long Han ◽  
Yan-Jie Gu ◽  
Kadambot H.M Siddique ◽  
...  

In semi-arid areas, alfalfa (Medicago sativa L.) is widely grown, but its growth is often restricted due to limited rainfall and soil nutrients, particularly phosphorus (P). Nutrient resorption is an effective strategy for dealing with nutrient shortages. Alleviation of these limited resources using film mulch and P fertilization—which are common practices in semi-arid areas—can affect the internal recycling of such nutrients. Little is known about such effects in alfalfa and the relationship between resorption efficiency and forage yield. We conducted a two-year field experiment in the semi-arid Loess Plateau of China using film mulch and P fertilization to investigate the response to long-term increasing soil water and P availability on leaf nitrogen (N), P, and potassium (K) concentrations and nutrient resorption characteristics in alfalfa. In green leaves, mulching significantly increased P concentration by an average of 5.5% but it had no significant effect on N concentration over two years, and it decreased K concentration by 16.1% in 2017. P fertilization significantly increased N concentrations to a greater degree in 2018 (8.1%) than 2017 (1.6%). P fertilization also significantly increased P concentrations by an average of 34.1% over two years. In contrast, P fertilization significantly decreased K concentration in the mulched treatment by an average of 17.3% in 2017 and 21.8% in 2018, but it had no effect in the no-mulch treatment. In senescent leaves, mulching significantly increased N concentration by an average of 3.9% and P concentration by an average of 16.7%, but it had no significant effect on K concentration over two years, while P fertilization significantly decreased N and K concentrations over two years by an average of 7.5%, and 32.8%, respectively. P fertilization significantly increased senesced P concentration by an average of 11.9% in 2017 and 17.5% in 2018; and year × mulching × P fertilization had a significant interaction on senesced leaf P concentration. For resorption efficiency, mulching decreased P resorption efficiency by an average of 3.0%, but it had no impact on N or K resorption efficiency, while P fertilization increased the N, P, and K resorption efficiencies in alfalfa by an average of 6.8%, 6.2%, and 76.4% over two years, respectively. Interactive effects of mulching and P fertilization were found on P and K resorption efficiencies over time. In addition, N and K resorption efficiencies were significantly higher in 2018 than in 2017. The application of P fertilizer without mulching resulted in positive correlations between forage yield and N, P, and K resorption efficiencies, but no correlations were observed under film mulch. That is, mulching changed the relationship between forage yield and N, P, and K resorption efficiencies in alfalfa, suggesting that N, P, and K resorption efficiencies may not be related to high yield. Our results provide new insights into the role of nutrient resorption in alfalfa in response to increasing soil water and P availability and the relationship between resorption efficiency and forage yield, which will help us to improve alfalfa yield in semi-arid regions.


2014 ◽  
Vol 154 (4) ◽  
pp. 511-525 ◽  
Author(s):  
Jiayin Pang ◽  
Jiyun Yang ◽  
Hans Lambers ◽  
Mark Tibbett ◽  
Kadambot H.M. Siddique ◽  
...  

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