The effects of elevated atmospheric CO2and soil P placement on cotton root deployment

2003 ◽  
Vol 255 (1) ◽  
pp. 179-187 ◽  
Author(s):  
S.A. Prior ◽  
H.H. Rogers ◽  
G.L. Mullins
Keyword(s):  
Soil P ◽  
2009 ◽  
Vol 60 (10) ◽  
pp. 987 ◽  
Author(s):  
Terry J. Rose ◽  
Zed Rengel ◽  
Qifu Ma ◽  
John W. Bowden

When the bulk of phosphorus (P) is located near the soil surface, spring drying of topsoil in Mediterranean-type climates can reduce P availability to crops and cause potential yield loss. In crop species that require a P supply during spring, deep-placement of P fertiliser has proved an effective method of improving P availability and grain yields; however, the spring P demand of field-grown canola (Brassica napus L.) and therefore potential response to deep P placement is not known. This study investigated the effect of deep- (0.17–0.18 m), conventional- (shallow, 0.07–0.08 m), split- (50% deep, 50% shallow), and nil-P fertiliser treatments on P accumulation and seed yields of canola in two field trials. In addition, a glasshouse experiment with different depths of P fertiliser placement and topsoil drying at different growth stages was conducted. In the glasshouse study, deep P placement resulted in greater P uptake by plants, but did not increase seed yields regardless of the time of topsoil drying. At the relatively high-soil-P field site (canola grown on residual P application from the previous year) in a dry season, there was no biomass response to any residual P fertiliser treatments, and P accumulation had ceased by mid flowering. At the low-P field site, P accumulation continued throughout flowering and silique-filling, and seed yields increased significantly (P ≤ 0.05) in the order of split- > deep- > shallow- > nil-P treatments. Improved seed yields in the split- and deep-P treatments appeared to be the direct result of enhanced P availability; in particular, P uptake during vegetative growth (winter) was higher in the treatments with deep P placement. A greater understanding of P accumulation by field-grown canola in relation to soil P properties is needed for better defining optimum P fertiliser placement recommendations.


2011 ◽  
Vol 60 (2) ◽  
pp. 343-358
Author(s):  
Péter Csathó ◽  
Marianna Magyar ◽  
Erzsébet Osztoics ◽  
Katalin Debreczeni ◽  
Katalin Sárdi

A szabadföldi trágyázási (tartam)kísérletek eredményeit talaj-, illetve diagnosztikai célú növényvizsgálatok segítségével tudjuk kiterjeszteni, általánosítani – figyelembe véve természetesen a kiterjesztés korlátait is. Célszerűnek láttuk ezen túl a talaj könnyen oldható tápelem-, közöttük P-tartalmát is meghatározni a hazánkban hivatalosan elfogadott AL- (ammónium-laktátos) módszer mellett az Európai Unióban és Észak-Amerikában alkalmazott P-tesztekkel is (CaCl2-, H2O-, Olsen-, Bray1-, LE-, Mehlich3- stb.) a hazai OMTK kísérletek talajmintáiban. A kísérleti helyek talajtulajdonságaiban megnyilvánuló jelentős különbségek lehetőséget adnak rá, hogy a talaj P-teszteket – és a növényi P-felvételt – jellegzetes hazai talajokon, sokszor szélsőséges talajparaméterek mellett vizsgáljuk. Az egyes P-szintek között a 28 év átlagában mintegy évi 50 kg P2O5·ha-1volt a különbség. A P0-szinten mért P-tartalmak jól jelezték az egyes kísérleti helyek talajának eltérő P-ellátottságát, illetve, közvetve, fizikai féleségében, pH és mészállapotában meglévő különbségeket. A P2-szinten – a hazai talajokra, P-igényes növényekre a hazai szabadföldi P-trágyázási tartamkísérleti adatbázisban talált összefüggésekre alapozott – új AL-P határértékek szerint csupán a bicsérdi csernozjom barna erdőtalajon nem javult a P-ellátottság legalább a „jó” szintig. Vizsgálataink megerősítették az AL-módszer függőségét a CaCO3-tartalomtól: a Mehlich3 módszerrel való összefüggésben a karbonátmentes és a karbonátos talajok csoportja erőteljesen elkülönült egymástól. Az AL-P korrekció elvégzése, azaz az AL-P értékeknek egy standard talajtulajdonság-sorra való konvertálása (KA: 36; pH(KCl): 6,8; CaCO3: 0,1%) látványosan csökkentette az AL-módszernek a talaj CaCO3-tartalmától való függőségét. Az AL-P és Olsen-P, valamint a korrigált AL-P és Olsen-P tartalmak összehasonlításában ugynakkor ugyanez az összefüggés nem volt állapítható, ami arra utal, hogy az Olsen módszer bizonyos fokig szintén pH- és mészállapot függő. Kísérleti eredményeink megerősítették a Sarkadi-féle AL-P korrekciós modell helytálló voltát. Fenti megállapításunkat ugyanakkor a növényi P-tartalmakkal való összefüggéseknek is igazolniuk kell. Szükséges tehát a talajvizsgálati eredményeknek a diagnosztikai célú növényvizsgálatokkal, valamint a terméseredményekkel való összevetése. A tartamkísérletek talajai lehetőséget nyújtanak a környezetvédelmi célú P-vizsgálatok értékelésére, a talaj P-feltöltöttsége környezeti kockázatának becslésére. Ezekkel a kérdésekkel a cikksorozat további részeiben kívánunk foglalkozni.


Author(s):  
Nadav Samin

Why do tribal genealogies matter in modern-day Saudi Arabia? What compels the strivers and climbers of the new Saudi Arabia to want to prove their authentic descent from one or another prestigious Arabian tribe? This book looks at how genealogy and tribal belonging have informed the lives of past and present inhabitants of Saudi Arabia and how the Saudi government's tacit glorification of tribal origins has shaped the powerful development of the kingdom's genealogical culture. The book presents the first extended biographical exploration of the major twentieth-century Saudi scholar Hamad al-Jāsir, whose genealogical studies frame the story about belonging and identity in the modern kingdom. It examines the interplay between al-Jāsir's genealogical project and his many hundreds of petitioners, mostly Saudis of nontribal or lower status origin who sought validation of their tribal roots in his genealogical texts. Investigating the Saudi relationship to this opaque, orally inscribed historical tradition, the book considers the consequences of modern Saudi genealogical politics and how the most intimate anxieties of nontribal Saudis today are amplified by the governing strategies and kinship ideology of the Saudi state. Challenging the impression that Saudi culture is determined by puritanical religiosity or rentier economic principles, the book shows how the exploration and establishment of tribal genealogies have become influential phenomena in contemporary Saudi society. Beyond Saudi Arabia, this book casts important new light on the interplay between kinship ideas, oral narrative, and state formation in rapidly changing societies.


2019 ◽  
Vol 103 (1) ◽  
pp. 43-45 ◽  
Author(s):  
Carlos Crusciol ◽  
João Rigon ◽  
Juliano Calonego ◽  
Rogério Soratto

Some crop species could be used inside a cropping system as part of a strategy to increase soil P availability due to their capacity to recycle P and shift the equilibrium between soil P fractions to benefit the main crop. The release of P by crop residue decomposition, and mobilization and uptake of otherwise recalcitrant P are important mechanisms capable of increasing P availability and crop yields.


Agriculture ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 157
Author(s):  
Jean Trap ◽  
Patricia Mahafaka Ranoarisoa ◽  
Usman Irshad ◽  
Claude Plassard

Plants evolve complex interactions with diverse soil mutualist organisms to enhance P mobilization from the soil. These strategies are particularly important when P is poorly available. It is still unclear how the soil P source (e.g., mineral P versus recalcitrant organic P) and its mobility in the soil (high or low) affect soil mutualist biological (ectomycorrhizal fungi, bacteria and bacterial-feeding nematodes) richness—plant P acquisition relationships. Using a set of six microcosm experiments conducted in growth chamber across contrasting P situations, we tested the hypothesis that the relationship between the increasing addition of soil mutualist organisms in the rhizosphere of the plant and plant P acquisition depends on P source and mobility. The highest correlation (R2 = 0.70) between plant P acquisition with soil rhizosphere biological richness was found in a high P-sorbing soil amended with an organic P source. In the five other situations, the relationships became significant either in soil conditions, with or without mineral P addition, or when the P source was supplied as organic P in the absence of soil, although with a low correlation coefficient (0.09 < R2 < 0.15). We thus encourage the systematic and careful consideration of the form and mobility of P in the experimental trials that aim to assess the role of biological complexity on plant P nutrition.


Agronomy ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 109
Author(s):  
Theocharis Chatzistathis ◽  
Evgenia Papaioannou ◽  
Anastasia Giannakoula ◽  
Ioannis E. Papadakis

One of the most challenging topics for the sustainable agriculture is how to decrease high fertilization rates. A pot experiment, exploring the effects of zeolite (ZEO) and/or vermiculite (VER) as soil amendments, comparing to the soil application of a controlled release fertilizer (CRF), was realized in chestnut plants. Various parameters related to soil fertility, and plant growth, nutrition, and physiology were investigated to gain knowledge towards more sustainable management. After ZEO application and in comparison to CRF, an impressive boost in soil K was achieved. Moreover, soil P and Zn levels were higher in the VER-treated soil, compared to CRF. Leaf K and Ca concentrations were significantly higher in ZEO, compared to the VER treatment; the highest foliar N and Zn concentrations were measured in CRF and VER, respectively. However, significantly lower foliar Mn and Cu were found in VER. The highest root biomass produced in the ZEO treated plants. For most nutrients, their total uptake per plant was higher in CRF and ZEO. Finally, photosynthetic rates were higher in VER (mainly due to non-stomatal factors) and CRF (mainly due to stomatal factors). Our data open a discussion towards the application of ZEO and/or VER as soil amendments in chestnut nurseries and orchards, aiming at partially decreasing fertilization rates and boosting sustainable nutrient management.


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