Increased risk of zinc deficiency in wheat on soils limed to correct soil acidity.
When newly cleared, ~45% of the 18 million ha of land used for agriculture in south-western Australia (SWWA) was deficient in zinc (Zn) for grain production of spring wheat (Triticum aestivum L.), the major crop in the region. Fertiliser Zn needed to be applied to wheat when it was first sown in these soils (Gartrell and Glencross 1968). Those original applications of Zn had a long-lasting residual value and maintained grain production of wheat for 10-15 years and so only infrequent re-application of Zn fertiliser has been required (Brennan 1996, 2001).
The originally Zn-deficient soils in SWWA included both acidic and alkaline soils (Gartrell and Glencross 1968). Agricultural production on the acidic to neutral soils has eventually acidified the soils and lime has been recommended for most of these soils to maintain grain production of wheat (Dolling et al. 1991; Dolling and Porter 1994). However, application of lime to these soils has often induced Zn deficiency in wheat as has been reported elsewhere in previous research (Lopez 1980). Zinc deficiency is attributed to increasing Zn sorption by soil with rises in pH (Barrow 1993, 1999; Barrow and Whelan 1998), which in turn reduces uptake of Zn by plants (Jeffery and Uren 1983; Lindsay 1991; Whelan and Barrow 1998).
The widespread use of lime to treat acidity has the potential to decrease the residual value of added Zn fertiliser and to require revised Zn fertiliser practices in SWWA. The effect of soil pH and other soil properties on the residual value of fertiliser Zn in unlimed soils has been studied in SWWA and the rate of decline in the residual value (RV) of Zn was reasonably well predicted by 3 soil properties: soil p[H.sub.Ca], %clay, and %organic carbon (Brennan and Gartrell 1990). However, the effect of CaC[O.sub.3]-induced increases in soil pH on Zn forms and availability has not been investigated. We used a Zn deficient acidic sand collected in SWWA and added either no calcium carbonate or amounts of calcium carbonate to produce soils with pH values 4.9, 5.8, and 7.4. For each of the 3 soils we incubated 5 amounts of Zn for 4 different periods of time (0-180 days) before growing wheat; it was possible to determine the residual value of the incubated Zn treatments for producing dried wheat shoots relative to the effectiveness of freshly applied Zn to produce the shoots. The concentration of Zn in the dried shoots was measured, and the Zn content in the dried shoots (Zn concentration multiplied by yield of dried shoots) was also used to calculate the residual value of the incubated Zn treatments. We measured Zn concentration in young tissue (apex and the youngest emerged leaf) and in the rest of the shoots to determine critical tissue test value, which was the Zn concentration in the 2 tissue samples that was related to 90% of the maximum yield of dried whole wheat shoots. Just before sowing wheat, we collected soil samples from all treatments to measure DTPA-extractable Zn, and the soil test values were also used to calculate the residual value of the incubated Zn treatments. The soil test values were related to yields of dried wheat shoots and critical soil test Zn, the soil test value that was related to 90% of the maximum yield of dried shoots, was determined.
Materials and methods
An acidic sand known to be deficient in Zn for wheat production was used for the experiment. The soil was collected from a site that contained remnants of native vegetation and had not been fertilised for agriculture. The <4 mm fraction of the top 0.10 m of the soil was used. The collection site for the soil was South Stirlings (34[degrees]35'S, 118[degrees]14'E), about 60 km north-east of Albany (35[degrees]S, 117[degrees]52'E), SWWA. The soil was a brown loamy fine sand, known locally as Waychinicup sand (Bettenay and Poutsma 1962). Further soil classifications, and some properties of the soil, are listed in Table 1.
The experiment comprised 3 calcium carbonate (CaC[O.sub.3]) treatments, 5 amounts of applied Zn, and 5 Zn incubation treatments in moist soil, replicated 3 times.
Subsamples of 3000 g of soil were placed in plastic pots, 170 mm diameter by 190 mm high, lined with polyethylene bags. Three levels of finely ground CaC[O.sub.3] (0, 7.5, and 15 g CaC[O.sub.3]/pot) were applied and mixed through the soil by shaking soil in the polyethylene bags. Analytical grade CaC[O.sub.3] was used and the contamination of Zn in the CaC[O.sub.3 was <0.1 mg/kg. The CaC[O.sub.3] was then incubated with moist soil for 6 weeks at 22[degrees]C [+ or -] 1[degrees]C. Sufficient deionised water was added to the soil in each pot to achieve a moisture content of 11%, the gravimetric field capacity of the soil. Each pot was sealed in polyethylene bags to prevent water loss from the soil during the incubation period. At the end of the incubation period, subsamples of soil were collected from each pot to measure soil pH in 0.01 M Ca[Cl.sub.2] using the procedures described by Rayment and Higginson (1992). The pH of the soil not treated with CaC[O.sub.3] was 4.9 (hereafter called Soil A). The pH of the soil treated with 7.5 g CaC[O.sub.3]/pot was 5.8 (hereafter called Soil B), and the pH of the soil treated with 15 g CaC[O.sub.3]/pot was 7.4 (hereafter called Soil C). The soils in all pots were then allowed to air-dry in the glasshouse.
The Zn treatments were then applied to the soils in the pots. The 5 amounts of Zn applied, as solutions of ZnS[O.sub.4].7[H.sub.2]0, were (mg Zn/pot): 0 ([Zn.sub.0]), 0.10 ([Zn.sub.1]), 0.20 ([Zn.sub.2]), 0.40 ([Zn.sub.3]), and 0.80 ([Zn.sub.4]). There were 5 Zn incubation treatments (0, 30, 60, 120, and 180 days). The Zn treatments were first applied to the 180-day Zn-incubation treatment pots. After the soils treated with Zn had dried, the soil in each pot was thoroughly shaken in the polyethylene bag to mix the Zn through the whole soil. The pots were then watered to field capacity, using deionised water, and the pots sealed in polyethylene bags to prevent loss of moisture from the pots during the Zn incubation at 22[degrees]C [+ or -] 1[degrees]C. The same procedure was repeated 60, 120, 150, and 180 days later for the Zn treatments incubated for 120, 60, 30, and 0 days, respectively. Two days before adding the Zn treatments to the 0-day Zn-incubation treatment, the soils that had been incubating in the 30-180-day Zn-incubation treatments were allowed to air-dry in the glasshouse. Then the Zn treatments were applied to the 0-day Zn-incubation treatment pots; these were the freshly applied Zn treatments. To ensure Zn was the only nutrient limiting plant growth; basal nutrient solutions were applied to all pots and comprised (mg/pot): 250 N[H.sub.4]N[O.sub.3], 328 [K.sub.2]S[O.sub.4], 550 K[H.sub.2]P[O.sub.4], 68 MgS[O.sub.4].7[H.sub.2]0, 100 Ca[Cl.sub.2], 15 CuS[O.sub.4].5[H.sub.2]0, 45 MnS[O.sub.4].5[H.sub.2]0, 30 FeS[O.sub.4].7[H.sub.2]0, 0.90 COS[O.sub.4].7[H.sub.2]0, 0.80 [Na.sub.2]Mo[O.sub.4].2[H.sub.2]0, and 0.9 [H.sub.3]B[O.sub.3]. The Zn present as an impurity in the macronutrient salts (N, K, P, Mg, and Ca) was removed with dithizone-chloroform, as described by Hewitt (1966). When the soils had dried after adding the freshly applied Zn treatments to the 0-day incubation treatments, and basal nutrient solutions were added to all the pots, the soil in each pot was thoroughly mixed by shaking the soil in the polyethylene bag.
The pots were completely randomised in the glasshouse. The soils were then watered to 75% field capacity before sowing wheat. The wheat seed was sieved to uniform size (41 [+ or -] 2 mg per seed) for sowing in the experiment. Twelve seeds of wheat (cv. Spear), with a seed Zn concentration of 13 mg/kg, were sown 20 mm deep in each pot before thinning to 8 plants per pot at 14 days after sowing. For the first 21 days after sowing, soils were maintained at 75% of field capacity using deionised water. Thereafter, the pots were maintained at field capacity (11% w/w) by daily watering to weight. The pots were completely randomised in the glasshouse, and were re-randomised daily in the glasshouse while watering. Temperatures in the glasshouse for the plant growth (mid-September to early-November) were set at 18[degrees]C day and 13[degrees]C night, [+ or -] 1[degrees]C.
During the growth of the plants, nitrogen [ammonium nitrate (purified to remove Zn contamination as described above), 250 mg/pot] was applied at l0 days after seedling emergence and thereafter every 7 days.
Just before sowing, soil samples (50 g/pot) were taken from each pot using a stainless steel tube to measure DTPA-extractable Zn using procedures described by Lindsay and Norvell (1978).
At 45 days after sowing, the plants were cut at ground level and the young growth (apex and the youngest emerged leaf) of each plant (youngest mature growth, YMG) was separated from the remainder of the shoots (ROS) (Reuter et al. 1997a). The total weight of dried shoots (TWS) was the sum of the dried weight of YMG and ROS. The cut material was dried at 80[degrees]C for 48 h and weighed. After weighing, the YMG and ROS were separately ground and digested in a nitric and perchloric acid mixture (Johnson and Ulrich 1959) and the concentration of Zn in the digest was measured by atomic absorption spectrophotometry (Allen 1961).
After wheat plants were harvested, soil samples were collected from each pot to measure soil pH using procedures described by Rayment and Higginson (1992).
Analysis of data
Data for the relationship between yield of dried shoots and the amount of Zn applied were adequately described by a rescaled Mitscherlich equation of the form (Barrow and Mendoza 1990):
(1) y = a-b exp(-[(cx).sup.n])
where y is TWS (g/pot), x is the amount of Zn applied (mg Zn/pot), and a, b, and c are coefficients. Coefficient a (g/pot) provided an estimate of the asymptote or maximum yield plateau. The value of the a coefficient was used as the maximum yield to calculate percentage of the maximum (relative) yield. Coefficient b (g/pot) estimated the difference between the asymptote and the intercept on the yield (y) axis at x = 0 and so estimated the maximum yield response to applied Zn. Coefficient c (pot/mg Zn) described the shape of the relationship and governed the rate at which y (the yield response) increased as x (the amount of Zn applied) increased. Coefficient n also described the shape of the relationship such that when n = 1.0 the response curve is exponential, but as the value of n becomes increasingly larger than 1.0 the response curve becomes increasingly sigmoid (Barrow and Mendoza 1990). Mean data were fitted to the equation by non-linear regression using a computer program written in compiler BASIC (Barrow and Mendoza 1990). The simplex method (Nelder and Mead 1965) was used to locate the least square estimates of the non-linear coefficients.
Shoot yield data were used to calculate the residual value (R[V.sub.yield]) of the incubated Zn treatments. This was done for each of the 3 soils by calculating the effectiveness of incubated Zn for producing dried shoots relative to the effectiveness of freshly applied Zn to produce dried shoots. All the incubated and freshly applied Zn treatments for all 3 soils supported the same maximum yield plateau (Fig. 1). Under these circumstances, R[V.sub.yield] values can be calculated using the c coefficient of Eqn 1 (Barrow and Campbell 1972; Barrow 1975; Barrow and Mendoza 1990). The R[V.sub.yield] values for the Zn treatments were calculated by dividing the c coefficient of the incubated and freshly applied Zn treatments for all 3 soils by the c coefficient for the freshly applied Zn treatment for Soil A (not treated with calcium carbonate), so that by definition the R[V.sub.yield] for the freshly applied Zn treatment of Soil A is 1.00.
[FIGURE 1 OMITTED]
Data for the relationship between Zn content of dried shoots ([Zn concentration in YMG multiplied by the yield of YMG] plus [Zn concentration in ROS multiplied by yield of ROS]) and the amount of Zn applied were not fitted to the rescaled Mitscherlich Eqn 1. This was because a maximum plateau for the Zn content of shoots was not defined (see Fig. 2). Instead, for the relationship between Zn content in dried shoots and the amount of Zn applied, data for the [Zn.sub.0], [Zn.sub.1], and [Zn.sub.2] treatments were adequately described by a linear equation:
(2) y = A + Bx
[FIGURE 2 OMITTED]
where y is the Zn content in the dried shoots ([micro]g Zn/pot), x is the amount of Zn applied (mg Zn/pot), and A and B are coefficients. Coefficient A provided an estimate of the Zn content of dried shoots derived from indigenous soil Zn. Coefficient B estimated the slope for the initial part of the relationship, and so estimated the increase in Zn content in dried shoots per unit of added Zn fertiliser. The RV values calculated using Zn content data (R[V.sub.content]) were determined by dividing the B coefficient for all Zn treatments by the B coefficient for the freshly applied Zn treatment of Soil A. Therefore, by definition, the R[V.sub.content] for the freshly applied Zn treatment for Soil A is 1.00.
The relationship between yield of dried TWS, expressed as relative yield, as the dependent variable (y-axis), and the concentration of Zn in either YMG or in ROS, as the independent variable (x-axis), was used to define their critical Zn concentrations. The critical value is the Zn concentration in either YMG or in ROS that was related to 90% of the maximum yield of TWS (Ulrich and Hills 1967). The value of the a coefficient of the rescaled Mitscherlich Eqn 1 fitted to data for the relationship between yield of TWS and the amount of Zn applied was used as the maximum yield to calculate relative yield. Data for the relationship between yield of dried shoots and the Zn concentration in plant tissue were described by a Mitscherlich equation of the form (Barrow and Mendoza 1990):
(3) y = a-b exp(-cx)
where y is the relative yield of TWS (%), x is the Zn concentration in YMG or ROS (mg/kg), and a, b, and c are as described for Eqn 1. Separate equations needed to be fitted to the YMG and ROS data, and the fitted equations were used to calculate the critical Zn concentrations in YMG or ROS.
Data for the relationship between soil test Zn and the amount of Zn applied were adequately described by linear Eqn 2 where y is the soil test Zn (mg Zn/kg soil) and x is the amount of Zn applied (mg Zn/pot). Coefficient A is the intercept and estimated the amount of indigenous Zn extracted from soil. Coefficient B is the slope and estimated the extractability of Zn from soil (referred to hereafter as extractability). These soil test data were used to calculate R[V.sub.soil] values, by dividing the B coefficient for all the Zn treatments in all 3 soils by the B coefficient for the freshly applied Zn treatment for Soil A. Therefore, by definition, the R[V.sub.soil for the freshly applied Zn treatment for Soil A is 1.00.
Data for the relationship between yield of dried shoots and soil test Zn were fitted to Mitscherlich Eqn 3, where y is the yield of dried shoots (g/pot), x is the soil test Zn (mgZn/kg soil), and a, b, and c are coefficients. The fitted equation was then used to calculate critical soil test Zn, which is the soil test value that was related to 90% of the maximum shoot yield. The value of the a coefficient was used to calculate 90% of the maximum yield.
The pH values measured on subsamples of the 3 soils collected at the end of the 6-week incubation period of soil with CaC[O.sub.3], and again on separate subsamples at the completion of plant growth, were not significantly different. The values were pH 4.9 for the untreated soil (Soil A), 5.8 for soil treated with 7.5 g CaC[O.sub.3] per pot (Soil B), and 7.4 for soil treated with 15 g CaC[O.sub.3] per pot (Soil C). Other soil properties in Table 1 were also unaffected by the CaC[O.sub.3] treatments.
Symptoms of Zn deficiency of wheat
Visual symptoms of Zn deficiency were observed about 3 weeks after emergence of the wheat seedlings in all soils. The deficient plants were stunted after about 4 weeks; these symptoms were observed on the nil Zn ([Zn.sub.0]) and [Zn.sub.1] treatments for all soils which were all Zn-deficient and had not been treated with fertiliser before collection. The deficiency symptoms were a pale longitudinal strip along both sides of the midrib of the youngest leaf. The mid-section along the length of the leaf became necrotic and leaves collapsed as the deficiency worsened. Symptoms were more severe for soil that had been incubated with the largest amount of calcium carbonate (soil C) and, for all 3 soils, when Zn was incubated with the soil for 180 days.
Yield of dried shoots
The dried shoots showed large yield increases (responses) to applied Zn in all 3 soils (Fig. 1). The responses were largest for freshly applied Zn, and decreased with increasing pH of soil and with increasing days of incubation of Zn in moist soil before sowing wheat (Fig. 1). Consequently, as determined using yield of dried shoots, relative to freshly applied Zn for Soil A, the residual value (R[V.sub.yield]) of incubated Zn decreased with increasing soil pH and with increasing time of incubation of applied Zn with moist soil (Fig. 2a, Table 2). The freshly applied and incubated Zn treatments produced similar yields for the nil-Zn treatments and maximum yield plateaus regardless of soil pH (Fig. 1, Table 2). Consequently, R[V.sub.yield] values were similar whether calculated relative to the freshly applied Zn treatment of each soil or relative to the freshly applied treatment of Soil A.
[FIGURE 1 OMITTED]
Zn content of dried shoots
Zn contents of dried shoots were greatest for freshly applied Zn and, per unit of applied Zn, tended to decrease with increasing pH of soil and increasing period of incubation of applied Zn in moist soil before sowing wheat (Fig. 3). Consequently, as determined using Zn content in dried shoots, the R[V.sub.content] values tended to decrease with increasing pH of soil and with increasing period of incubation of Zn in moist soil (Fig. 2b, Table 3).
[FIGURE 3 OMITTED]
Critical concentration of Zn in plant parts
The relationship between yield of TWS and the Zn concentration was different for YMG and ROS, but for either YMG or ROS was similar for the 3 soils and the 5 Zn incubation treatments (Fig. 4). The Zn concentration that was related to 90% of the maximum TWS yield was about 13 mg/kg for YMG and 23 mg/kg for ROS.
[FIGURE 4 OMITTED]
Soil test Zn
Soil test Zn (DTPA procedure) increased as more Zn was applied in all 3 soils (Fig. 5). However, per unit of applied Zn, soil test values tended to decrease with increasing pH of soil and with increasing period of incubation of Zn with moist soil (Fig. 2c). Consequently, extractability (value of B coefficient of linear Eqn 2 fitted data for the relationship between soil test Zn and the amount of Zn applied) and RVsoil values both tended to decrease with increasing pH of soil and incubation period of Zn with soil (Table 4, Fig. 5).
[FIGURE 5 OMITTED]
Critical DTPA soil test Zn
The relationship between yield of TWS and soil test Zn was the similar for the 3 soils and the 5 Zn incubation treatments (Fig. 6a). For clarity, we have used different symbols for the 5 Zn incubation treatments for Soils A and C in Fig. 6b, and within error, the relationships for all data were similar and could be fitted to the same Mitscherlich Eqn 3. When we fitted separate equations to data for each soil, calcium carbonate, and Zn-incubation treatment, compared to fitting all the data to the same equation, there was no significant reduction in the residual sum of squares (data not shown). Consequently, the critical soil test value (the soil test value that was related to 90% of the maximum yield), determined from the same or separate equations fitted to the data, was similar for all 3 soils. The soil test Zn value that was related to 90% of the maximum yield of dried wheat shoots (critical DTPA Zn value) was 0.14 mg Zn/kg soil for the 3 soils.
[FIGURE 6 OMITTED]
We showed that increasing the pH of soil by incubating calcium carbonate with soil decreased the residual value of applied Zn. An increase in soil pH decreases Zn availability for plant uptake (Seatz et al. 1959) and liming soils often leads to Zn deficiency in plants (Lopez 1980). Therefore, it is highly likely that the residual value of Zn would be low in soils with high soil pH, particularly when there is much free calcium carbonate present in the soil. However, few soils in SWWA naturally contain free calcium carbonate (McArthur 1991). By contrast, most sandy soils used for cropping in SWWA have acidified, particularly in the 0.10-0.40m zone of soil, called subsurface acidity (Dolling et al. 1991; Dolling and Porter 1994). Subsurface acidity is ameliorated by adding sufficient lime to the topsoil to raise the pH of the top 0.10m of soil to [greater than or equal to]5.5, when alkali produced in the limed topsoil starts to move down into the subsoil (Whitten et al. 2000). The pH of the top 0.10 m of acidified sandy soils in SWWA is typically 3.8-4.5, so up to 4t/ha lime needs to be applied to the soils to achieve a pH in the topsoil of [greater than or equal to]5.5 and is mostly achieved by applying several applications in successive years. Zn deficiency is frequently identified in wheat crops in SWWA after liming, including in long-term lime experiments in SWWA (C. Gazey, unpublished data). Until now the implications of liming for Zn availability and residual effectiveness of soil Zn have not been explored. In the present study treating an acid sandy soil with calcium carbonate increased the pH of the soil, which increased retention of Zn by soil and so reduced the residual value of Zn measured using yield and Zn content of dried wheat shoots, and soil test Zn. All these parameters indicated reduced effectiveness of the applied Zn for wheat production. Whilst the most severe effect of calcium carbonate on Zn effectiveness was at pH 7.4, even the relatively modest increase of soil pH to 5.8 decreased effectiveness of Zn fertiliser. Hence, the decrease in residual value can occur even when modest amounts of lime have been applied to soil and is not simply a consequence of over-liming.
The present results have implications for soils where it has been some years since Zn fertiliser was last applied and where the Zn status of the soil has become marginal or deficient for wheat production. These soils may need fertiliser Zn applications even before liming, but particularly when the soils are limed. Before liming soils, Zn status of crops should be assessed by plant sampling as an indication of likely deficiency in soil. If the Zn concentrations in plant parts indicate marginal or deficient Zn supply, the deficiency can be avoided in future crops by soil application of Zn at planting or minimised by foliar applications during crop growth (Brennan 2000). Alternatively, farmers should collect soil samples to measure soil test Zn before applying lime and sowing the next crop. Critical soil test Zn values for individual soils depend on soil pH, clay, and organic carbon, but critical DTPA-Zn values are about 0.20 mg Zn/kg for sandy soils of SWWA (Brennan 1992). If the soil test results indicate Zn deficiency is likely, then it would be advisable for farmers to apply fertiliser Zn. An alternative strategy is always to apply fertiliser Zn when soils are limed to reduce the likelihood of Zn deficiency reducing grain yields.
Liming acid soils in high rainfall areas of SWWA reduced the concentrations of Zn, manganese (Mn), and copper (Cu) in pasture (Bolland et al. 2002). In addition, both Zn and Mn deficiency of wheat are frequently identified after liming in SWWA (C. Gazey, unpublished data). Therefore, in addition to Zn, both Mn and Cu deficiency may be induced in wheat crops following liming of acidified soils in SWWA.
The incubation of Zn with moist soil decreased the availability of Zn regardless of the pH of the 3 soils. The decrease in plant-available Zn due to the incubation is attributed to continued reaction of Zn with soil constituents (organic matter, clay, iron and aluminium oxides) increasing Zn retention by soil (Brennan 1990; Brennan and Gartrell 1990; Barrow 1999). Incubation of Cu (Brennan et al. 1980, 1984) and Mn (Brennan and Bolland 2003, 2004) in moist soil has also been found to decrease the effectiveness of fertiliser Cu and Mn for the production of several crop species.
Previous studies, using stepwise multiple linear regression analysis, have identified several soil properties, including soil [pH.sub.Ca], clay content (%), organic carbon content (%), and free calcium carbonate (%), as influencing plant yield responses to applied Zn for different crop species (Martens et al. 1966; Martens 1968; Brennan and Gartrell 1990). Jurinak and Bauer (1956) showed that Zn is more strongly adsorbed onto clay minerals at alkaline pH values. At high soil pH, Zn is more strongly adsorbed onto the surface of silicate clays and oxides (Lindsay 1978, 1981; Jeffery and Uren 1983; Harter 1983; Jahiruddin et al. 1985, 1986), and hence the availability of Zn to plants is diminished.
The critical tissue test values we obtained for 45-day-old wheat plants (13 mg/kg for YMG, 23 mg/kg for ROS) were similar to values obtained in previous studies. Critical values for YMG in previous studies were about 14mg Zn/kg (Brennan et al. 1993, 2001; Weir and Cresswell 1994; Reuter et al. 1997a; Brennan 2001; Brennan and Bolland 2002), although Wilhelm et al. (1993) proposed a critical value of 18 mg Zn/kg in the youngest expanded blade (YEB) of wheat plants. Critical values for TWS of wheat obtained in previous studies were about 20 mg Zn/kg (Radjagukguk et al. 1980; Riley et al. 1992; Brennan et al. 1993, 2001; Reuter et al. 1997b). However, 32mg Zn/kg was found for TWS of wheat by Brennan and Bolland (2002). Hence, critical Zn concentrations derived for plants on unlimed soil appear to apply also to limed soils. This was also the case for critical DTPA soil test Zn in our study.
The effectiveness of Zn fertiliser for wheat declined with increasing period of contact of the fertiliser with the soil constituents and following application of calcium carbonate to the soil. Hence, we predict that a consequence of liming acid soils is to shorten the residual effectiveness of Zn fertiliser. If it has been many years since Zn fertiliser was last applied to the soil, then soil and plant testing is advisable before liming to assess the Zn status of soil and plants growing in the soil. If the soil is to be limed to ameliorate soil acidity, fertiliser Zn needs to be re-applied to the soil if the tests indicate a high likelihood of deficiency. An alternative strategy is always to apply fertiliser Zn (and Mn and Cu) as a precaution when soils are limed.
The Chemistry Centre (WA) measured soil properties and zinc concentrations in soil and plant tissue. The Grains Program of the Western Australian Department of Agriculture funded the work.
R. F. Brennan (A,D), M. D. A. Bolland (B), and R. W. Bell (C) (A) Department of Agriculture Western Australia, 444 Albany Highway, Albany, WA 6330, Australia.
(B) Department of Agriculture Western Australia, PO Box 1231, Bunbury, WA 6231, Australia; and School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
(C) School of Environmental Sciences, Murdoch University, South Street, Murdoch, WA 6151, Australia.
(D) Corresponding author. Email: email@example.com
Allen JE (1961) The determination of zinc in agricultural materials by atomic absorption spectrophotometry. Analyst 86, 531-534.
Barrow NJ (1975) The response to phosphorus of two annual pasture species. I. Effect of the soil's ability to adsorb phosphate on comparative phosphate requirement. Australian Journal of Agricultural Research 26, 137-143. doi: 10.1071/AR9750137
Barrow NJ (1993) Mechanisms of reaction of zinc with soil components. In 'Zinc in soil and plants'. (Ed. AD Robson) pp. 15-31. (Kluwer Academic Publishers: Dordrecht, The Netherlands)
Barrow NJ (1999) The four laws of soil chemistry: the Leeper lecture 1998. Australian Journal of Soil Research 37, 787-829. doi: 10.1071/SR98115
Barrow N J, Campbell NA (1972) Methods for measuring the residual value of fertilisers. Australian Journal of Experimental Agriculture and Animal Husbandry 12, 502-510. doi: 10.1071/EA9720502
Barrow NJ, Mendoza RE (1990) Equations for describing sigmoidal yield responses and their application to some phosphate responses by lupins and subterranean clover. Fertilizer Research 22, 181-194. doi: 10.1007/BF01120393
Barrow NJ, Whelan BW (1998) Comparing the effects of pH on the sorption of metals by soil, by goethite, and on uptake by plants. European Journal of Soil Science 49, 683-592. doi: 10.1046/j. 1365-2389.1998.4940683.x Bettenay E, Poutsma T (1962) Soils of the north Many Peaks, Western Australia. Division of Soils, Divisional Report No. 15/62, Perth, W. Aust.
Bolland MDA, Allen DG, Rengel Z (2002) Response of annual pastures to applications of limestone in the high rainfall areas of southwestern Australia. Australian Journal of Experimental Agriculture 42, 925-937. doi: 10.1071/EA01169
Brennan RF (1990) Reactions of zinc with soil affecting its availability to subterranean clover. II. Effect of soil properties on the relative effectiveness of applied zinc. Australian Journal of Soil Research 28, 303-310. doi: 10.1071/SR9900303
Brennan RF (1992) The relationship between critical concentration of DTPA-extractable Zn from the soil for wheat production and properties of south western Australian soils responsive to applied zinc. Communications in Soil Science and Plant Analysis 23, 747-759.
Brennan RF (1996) Availability of previous and current applications of zinc fertiliser using single superphosphate for the grain production of wheat on soils of south-western Australia. Journal of Plant Nutrition 19, 1099-1115.
Brennan RF (2000) Zinc. In 'The wheat book: Principles and practice'. Bulletin No. 4443. (Eds WK Anderson, JR Garlinge) pp. 98-99. (Agriculture Western Australia: South Perth, W. Aust.)
Brennan RF (2001) Residual value of zinc fertiliser for production of wheat. Australian Journal of Experimental Agriculture 41, 541-547. doi: 10.1071/EA00139
Brennan RF, Bolland MDA (2002) Relative effectiveness of soil-applied zinc for four crop species. Australian Journal of Experimental Agriculture 42, 985-993. doi: 10.1071/EA01066
Brennan RF, Bolland MDA (2003) Application of fertiliser manganese doubled yields of lentil grown on alkaline soils. Journal of Plant Nutrition 26, 1263-1276. doi: 10.1081/PLN-120020369
Brennan RF, Bolland MDA (2004) Comparing manganese sources for spring wheat grown on alkaline soils. Journal of Plant Nutrition 27, 95-109. doi: 10.1081/PLN-120027549
Brennan RF, Gartrell JW (1990) Reactions of zinc with soil affecting its availability to subterranean clover. I. The relationship between critical level of extractable zinc and its properties of Australian soils responsive to applied zinc. Australian Journal of Soil Research 28, 293-302. doi: 10.1071/SR9900293
Brennan RF, Armour JD, Reuter DJ (1993) Diagnosis of zinc deficiency. In 'Zinc in soil and plants'. (Ed. AD Robson) pp. 168-181. (Kluwer Academic Publishers: Dordrecht, The Netherlands)
Brennan RF, Bolland MDA, Siddique KHM (2001) Responses of cool season grain legumes and wheat to soil-applied zinc. Journal of Plant Nutrition 24, 727-741. doi: 10.1081/PEN-100103666
Brennan RF, Gartrell JW, Robson AD (1980) Reactions of copper with soil affecting its availability to plants. 1. Effect of soil type and time. Australian Journal of Soil Research 18, 447-459. doi: 10.1071/SR9800447
Brennan RF, Gartrell JW, Robson AD (1984) Reactions of copper with soil affecting its availability to plants. III. Effect of incubation temperature. Australian Journal of Soil Research 22, 165-172. doi: 10.1071/SR9840165
Day PR (1965) Particle fractionation and particle size analysis. In 'Methods of soil analysis, Part 1'. Agronomy Monograph No. 9. (Ed. CA Black) pp. 545. (American Soil Science Society: Madison, WI)
Dolling PJ, Porter WM (1994) Acidification rates in the central wheatbelt of Western Australia. Australian Journal of Experimental Agriculture 34, 1165-1175. doi: 10.1071/EA9941165
Dolling PJ, Porter WM, Robson AD (1991) Effect of soil acidity on barley production in the south-west of Western Australia. 2. Cereal genotypes and their response to lime. Australian Journal of Experimental Agriculture 31, 811-818. doi: 10.1071/EA9910811
Gartrell JW, Glencross RN (1968) Copper, zinc and molybdenum for new land crops and pastures- 1969. Journal of Agriculture--Western Australia 9, 517-521.
Harter RD (1983) Effect of soil pH on adsorption of lead, copper, zinc and nickel. Journal of the Soil Science Society of America 47, 47-51.
Hesse PR (1971) 'A textbook for soil chemical analysis. Iron, aluminium and manganese.' pp. 332-362. (J. Murray: London)
Hewitt EJ (1966) 'Sand and water culture methods used in the study of plant nutrition.' pp. 438-451. (Commonwealth Agricultural Bureaux: Farnham Royal, UK)
Jahiruddin M, Livesey NT, Cresser MS (1985) Observations on the effect of soil pH upon zinc absorption by soils. Communications in Soil Science and Plant Analysis 16, 909-922.
Jahiruddin M, Chambers BT, Livesey NT, Cresser MS (1986) Effect of liming on extractable Zn, Cu, Fe and Mn in selected Scottish soils. Journal of Soil Science 37, 603-615.
Jeffery JJ, Uren NC (1983) Copper and zinc species in the soil solution and the effect of soil pH. Australian Journal of Soil Research 21, 479-488. doi: 10.1071/SR9830479
Johnson CM, Ulrich A (1959) 'Analytical methods for use in plant analysis.' Bulletin of Californian Agricultural Experimental Station No. 766. (University of California: Berkeley, CA)
Jurinak JJ, Bauer N (1956) Thermodynamics of zinc adsorption on calcite, dolomite and magnesite-type minerals. Proceedings of the Soil Science Society of America 20, 466-471.
Lindsay WL (1978) Chemical reactions affecting the availability of micronutrients in soils. In 'Mineral nutrition of legumes in tropical and subtropical soils'. (Eds CS Andrew, EJ Kamprath) pp. 153-157. (CSIRO: Melbourne, Vie.)
Lindsay WL (1981) Solid phase-solution equilibria in soils. In 'Chemistry in the soil environment'. Special Publication No. 40. (Ed. RH Dowdy) pp. 183-201. (American Agronomy Society: Madison, WI)
Lindsay WL (1991) Inorganic equilibria affecting micronutrients in soils. In 'Micronutrients in agriculture'. (Eds JJ Morvedt, FR Cox, LM Shuman, RM Welch) pp. 89-112. (Soil Science Society of America: Madison, WI)
Lindsay WL, Norvell WA (1978) Development of a DTPA soil test for zinc, iron, manganese and copper. Proceedings of the Soil Science Society of America 42,421-428.
Lopez AS (1980) Micronutrients in soils of the tropics as constraints to food production. In 'Priorities for alleviating soil-related constraints to food production in the tropic', pp. 277-298. (International Rice Research Institute: Los Banos, Philippines)
Martens DC (1968) Plant availability of extractable boron, copper and zinc as related to selected soil properties. Soil Science 106, 23-28.
Martens DC, Chesters G, Peterson LA (1966) Factors controlling the extractability of soil zinc. Proceedings of the Soil Science Society of America 30, 67-69.
McArthur WM (1991) 'Reference soils of south-western Australia.' (Australian Society of Soil Science, WA Branch Inc.: Perth, W. Aust.)
Nelder JA, Mead R (1965) A simplex method for function minimisation. Computer Journal 7, 308-313.
Northcote KH (1979) 'A factual key for the recognition of Australian soils.' (Rellim Publications: Glenside, S. Aust.)
Radjagukguk B, Edwards DG, Bell LC (1980) Zinc availability to young wheat plants in Darling Downs black earths. Australian Journal of Agricultural Research 31, 1083-1096. doi: 10.1071/AR9801083
Rayment GE, Higginson FR (1992) 'Australian laboratory handbook of soil and water chemical methods.' (Inkata Press: Melbourne, Vic.)
Reuter DJ, Edwards DG, Wilhelm NS (1997b) Temperate and tropical crops. In 'Plant analysis: An interpretation manual'. (Eds DJ Reuter, JB Robinson) pp. 83-284. (CSIRO Publishing: Melbourne, Vic.)
Reuter DJ, Robinson JB, Peverill KI, Price GH, Lambert MJ (1997a) Guidelines for collecting, handling and analysing plant materials. In 'Plant analysis: An interpretation manual'. (Eds DJ Reuter, JB Robinson) pp. 55-70 (CSIRO Publishing: Melbourne, Vic.)
Riley MM, Gartrell JW, Brennan RE Hamblin J, Coates P (1992) Zinc deficiency in wheat and lupin in Western Australia is effected by the source of phosphate fertiliser. Australian Journal of Experimental Agriculture 32, 455-463. doi: 10.1071/EA9920455
Seatz LF, Sterges AJ, Kramer JC (1959) Crop response to zinc fertilisation as influenced by lime and phosphorus applications. Agronomy Journal 51, 451-459.
Soil Survey Staff (1990) 'Keys to Soil Taxonomy.' 4 edn. Soil Management Support Services Technical Monograph No. 6. (Virginia Polytechnic Institute and State University: Blacksburg, VA)
Stace HCT, Hubble GD, Brewer R, Northcote KH, Sleeman JR, Mulcahy MJ, Hallsworth EG (1968) 'A handbook of Australian soils.' (Rellim Publications: Glenside, S. Aust.)
Ulrich A, Hills FJ (1967) Principles and practices of plant analysis. In 'Soil testing and plant analysis. Part II, SSSA Special Publication Series 2'. pp. 11-24. (Soil Science Society of America: Madison, WI)
Walkley A, Black IA (1934) An examination of the Degjareff method of determining soil organic matter and a proposed modification of the chromic acid titration method. Soil Science 37, 29-38.
Weir RG, Cresswell GC (1994) 'Plant nutrient disorders. 4. Pastures and field crops.' (Inkata Press: Melbourne, Vic.)
Wilhelm NS, Hannam RJ, Bramford TA, Riggs JL, Allen JL, Auhl L (1993) Critical levels for zinc deficiency of field-grown wheat. In 'Proceedings of the 7th Australian Agronomy Conference'. Adelaide. (Eds GK McDonald, WD Bellotti, LM Shuman, RM Welch) pp. 119-121. (Australian Society of Agronomy: Parkville, Vic.)
Whitten MG, Wong MTF, Rate AW (2000) Amelioration of subsurface acidity in the south-west of Western Australia: downward movement and mass balance of surface-incorporated lime after 2-15 years. Australian Journal of Soil Research 38, 711-728. doi: 10.1071/SR99054
Manuscript received 1 November 2004, accepted 30 March 2005
Table 1. Soil classification and some properties of the top 0.10 m of the <4 mm fraction of the soil used The properties are listed for Soil A which was not treated with calcium carbonate, but, except for pH, the values for Soils B and C that were treated with calcium carbonate were similar and not statistically different (P > 0.05) from those listed for Soil A Classification Local name Waychinicup sand (A) Soil Survey Staff (1990) Typic Paleudalf Stace et al. (1968) Yellow duplex soil Northcote (1979) Dy4.83 Soil properties pH 1 : 5 soil: 0.01 m Ca[Cl.sub.2] (w/v) (B) 4.9 Clay (%) (C) 3.5 Organic carbon (%) (D) 0.8 Iron oxide (g/kg) (E) 5.4 Aluminium oxide (g/kg) (E) 1.0 DTPA-Zn (mg/kg) (F) 0.1 (A) Bettenay and Poutsma (1962). (B) Rayment and Higginson (1992). (C) Day (1965). (D) Walkley and Black (1934). (E) Sesquioxides (Hesse 1971). (F) Diethylenetriaminepentaacetic acid (DTPA) extractable Zn (Lindsay and Norvell 1978). Table 2. Values of the coefficients of the resealed Mitscherlich Eqn l (A) fitted to data for the relationship between yield of dried shoots (TWS) (g/pot) and the amount of zinc applied (mg Zn/pot), and, for each soil, R[V.sub.yield] Values Equation fitted: y = a-b exp (-[(cx).sup.n]), where y is the yield of dried shoots (g/pot), x is the amount of Zn applied (mg Zn/pot), a provides an estimate of the maximum yield plateau (g/pot), b is the yield response to added Zn (g/pot), c describes the shape of the relationship by estimating the rate at which y approaches the maximum yield plateau as the amount of Zn applied is increased, and n also affects the shape of the relationship. When the value of n is 1.00 the response curve is exponential, and as the value of n becomes increasingly > 1.00 the response curve becomes increasingly sigmoid (Barrow and Mendoza 1990). The coefficient of determination (R2) was >0.97 in all cases Relative Incubation Yield at response period nil Zn ([b/a]100) (days) (A) (g/pot) (%) a b Soil A 0 1.01 80 5.05 4.04 30 1.00 78 5.06 3.96 60 1.0 81 5.09 4.10 120 1.00 80 5.02 4.02 180 1.00 80 5.11 4.10 Soil B 0 1.00 80 5.04 4.03 30 1.00 78 5.06 3.97 60 1.00 80 5.03 4.02 120 1.00 80 5.09 4.08 180 1.0 81 5.37 4.37 Soil C 0 1.00 80 5.05 4.05 30 0.98 80 4.97 3.96 60 0.91 80 5.14 4.09 120 0.91 82 5.19 4.27 180 0.88 82 5.06 4.17 Incubation period (days) (A) c n R[V.sub.yield] (B) Soil A 0 33.40 0.73 1.00 30 28.37 1.00 0.85 60 15.67 0.55 0.47 120 12.21 0.73 0.37 180 9.42 0.58 0.28 Soil B 0 34.53 0.73 1.03 30 27.02 0.52 0.81 60 14.53 0.76 0.44 120 9.88 1.00 0.30 180 5.36 0.76 0.16 Soil C 0 34.12 1.00 1.02 30 16.07 1.00 0.50 60 11.70 0.58 0.35 120 6.76 1.49 0.20 180 4.85 2.44 0.15 (A) The 5 Zn incubation treatments were: 0 (freshly applied Zn treatment, no incubation), 30, 60, 120, 180 days incubation in moist soil before sowing wheat. (B) Calculated by dividing the c coefficient for each Zn treatment in all 3 soils by the c coefficient for the freshly applied Zn treatment for Soil A, so that, by definition, R[V.sub.yield] value for freshly applied Zn for Soil A is 1.00. Table 3. Values of the coefficients of linear Eqn 2 fitted to data for the relationship between Zn content of dried shoots ([micro]g/pot) and the amount of zinc applied (mg Zn/pot), and R[V.sub.content] values Linear Eqn 2 fitted: y = A + Bx, where y is the Zn content of dried shoots (g/pot), x is the amount of Zn applied (mg Zn/pot), A provides an estimate of the intercept where nil Zn is applied (mg/pot), and B estimates the slope of the relationship as the amount of Zn applied is increased. The coefficient of determination ([R.sup.2]) was >0.96 in all cases Incubation period (days) (A) A B R[V.sub.content] (B) Soil A 0 15.01 671 1.00 30 12.73 561 0.84 60 11.87 435 0.65 120 11.19 267 0.40 180 11.56 223 0.33 Soil B 0 12.13 671 1.00 30 10.32 499 0.74 60 9.17 360 0.54 120 9.08 251 0.37 180 7.62 169 0.25 Soil C 0 13.1 646 0.96 30 13.0 325 0.50 60 11.3 241 0.37 120 8.5 159 0.25 180 8.5 81 0.13 (A) There were 5 Zn incubation treatments: 0 (freshly applied Zn, no incubation), 30, 60, 120, and 180 days incubation in moist soil before sowing wheat. (B) Calculated by dividing the B (slope) coefficient for all Zn treatments in the 3 soils by the B coefficient for the freshly-applied Zn for Soil A. Consequently the R[V.sub.content] of freshly applied Zn for Soil A is, by definition, 1.00. Table 4. Values of the coefficients of the linear Eqn 2 fitted to data for the relationship between DTPA soil test Zn (mg/kg) and the amount of zinc applied (mg Zn/pot), and R[V.sub.soil] values Equation fitted: y = A + Bx, where y is the DTPA soil test Zn (mg/kg), x is the amount of Zn applied (mg Zn/pot), A provides an estimate of the intercept where nil Zn is applied (mg/pot), and B estimates the slope of the relationship as the amount of Zn applied is increased. The coefficient of determination ([r.sup.2]) was >0.93 in all cases Incubation period (days) (A) A B R[V.sub.soil] (B) Soil A 0 0.10 0.34 1.0 30 0.10 0.30 0.88 60 0.10 0.23 0.68 120 0.10 0.17 0.50 180 0.10 0.12 0.35 Soil B 0 0.10 0.32 0.94 30 0.10 0.26 0.76 60 0.10 0.20 0.59 120 0.10 0.16 0.47 180 0.10 0.13 0.38 Soil C 0 0.09 0.34 1.00 30 0.09 0.20 0.58 60 0.09 0.14 0.41 120 0.09 0.11 0.32 180 0.09 0.08 0.22 (A) There were 5 Zn incubation treatments: 0 (freshly applied Zn, no incubation), 30, 60, 120, and 180 days incubation in moist soil before sowing wheat. (B) Calculated by dividing the B (slope) coefficient for all Zn treatments in the 3 soils by the B coefficient for the freshly applied Zn for Soil A. Consequently the R[V.sub.soil] of freshly applied Zn for Soil A is, by definition, 1.00.
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|Author:||Brennan, R.F.; Bolland, M.D.A.; Bell, R.W.|
|Publication:||Australian Journal of Soil Research|
|Date:||Sep 1, 2005|
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