**5. Liming at planting and during formation of fruit orchards**

Because soil acidity is one of the most important factors limiting farm production in tropical regions, an experiment was performed to assess the effects of liming on soil fer‐ tility as well as the mineral nutrition and yield of guava (*Psidium guajava*) [12]. The lime‐ stone (CaO=45,6% and MgO=10,2%) was incorporated into the soil in July and August 1999 and the orchard was planted four months later (December 1999) using the Paluma cultivar propagated by cuttings. The corrective measure was applied manually on the en‐ tire field area, half incorporated with a moldboard plow and the other half applied and incorporated later using a disk plow (both implements reaching a depth of 0–30 cm). The soil was a dystrophic red latosol with base saturation (V) of 26% in the 0–20 cm lay‐ er. The experimental design consisted of random blocks of five treatments and four repe‐ titions. The limestone (reactivity = 94%) rates were 0, 1.85, 3.71, 5.56, and 7.41 ton ha-1. Chemical analysis of the soil was carried out for 78 months after liming and nutrient sta‐ tus and tree productivity were evaluated during five consecutive harvests. Liming changed chemical attributes of the soil related to acidity down to a depth of 60 cm, rais‐ ing the pH, Ca, Mg, sum of bases (SB) and base saturation (V) and diminishing potential acidity (H+Al).

During four years after orchard establishment, there was a significant correlation be‐ tween leaf and soil Ca (Table 1). In general, the same pattern occurred for Mg, with higher correlation of leaf Mg levels with Mg concentration in the soil between the rows. This can indicate that with the exhaustion of these bases in the tree rows, the roots of guava trees could absorb nutrients effectively between the rows, indicating the impor‐ tance of liming the entire area.

The yearly productivity during the experimental period (2002 to 2006) and the accumulated guava yields are presented in Figures 1a and 1b. Note the close fit of the production data to polynomial functions of the lime rates.


**d.** Liming and fertilization of orchards are determinant not only in the current growing season, but also for harvests to come because the inputs applied at one time will also supply the pending production by promoting the formation of new fruit-bearing shoots and building up nutrient reserves in the roots and the aboveground biomass for the fol‐

For a long time some fruit trees, especially those native to tropical regions like guava and carambola, were considered to be rustic plants, so their development was thought to be in‐ dependent of edaphoclimatic conditions as is still felt today about pastures. However, it is not possible to imagine that a soil can be exploited by a crop indefinitely without replenish‐ ing the nutrient reserves or correcting the acidity. However, due to the characteristics of per‐ ennial fruit-bearing plants, the difficulties of conducting long-term experiments under

Because soil acidity is one of the most important factors limiting farm production in tropical regions, an experiment was performed to assess the effects of liming on soil fer‐ tility as well as the mineral nutrition and yield of guava (*Psidium guajava*) [12]. The lime‐ stone (CaO=45,6% and MgO=10,2%) was incorporated into the soil in July and August 1999 and the orchard was planted four months later (December 1999) using the Paluma cultivar propagated by cuttings. The corrective measure was applied manually on the en‐ tire field area, half incorporated with a moldboard plow and the other half applied and incorporated later using a disk plow (both implements reaching a depth of 0–30 cm). The soil was a dystrophic red latosol with base saturation (V) of 26% in the 0–20 cm lay‐ er. The experimental design consisted of random blocks of five treatments and four repe‐ titions. The limestone (reactivity = 94%) rates were 0, 1.85, 3.71, 5.56, and 7.41 ton ha-1. Chemical analysis of the soil was carried out for 78 months after liming and nutrient sta‐ tus and tree productivity were evaluated during five consecutive harvests. Liming changed chemical attributes of the soil related to acidity down to a depth of 60 cm, rais‐ ing the pH, Ca, Mg, sum of bases (SB) and base saturation (V) and diminishing potential

During four years after orchard establishment, there was a significant correlation be‐ tween leaf and soil Ca (Table 1). In general, the same pattern occurred for Mg, with higher correlation of leaf Mg levels with Mg concentration in the soil between the rows. This can indicate that with the exhaustion of these bases in the tree rows, the roots of guava trees could absorb nutrients effectively between the rows, indicating the impor‐

The yearly productivity during the experimental period (2002 to 2006) and the accumulated guava yields are presented in Figures 1a and 1b. Note the close fit of the production data to

present research funding support tend to discourage researchers.

**5. Liming at planting and during formation of fruit orchards**

lowing seasons.

180 Soil Fertility

acidity (H+Al).

tance of liming the entire area.

polynomial functions of the lime rates.

R: in tree rows; B: between tree rows. \*\*, \* and ns: significant at p < 0.01, p < 0.05 and not significant, re‐ spectively. The values are means of four repetitions each year.

**Table 1.** Correlation coefficients between Ca and Mg concentrations in the soil (0–20 cm) between and in the tree rows and leaf Ca and Mg concentrations in guava trees over the experimental period

**Figure 1.** Effect of applying limestone on guava fruit yield for yearly harvests (a) and cumulated production (b).

Leaf Ca and Mg concentrations increased with lime rate and showed quadratic effects (Figure 2).

**Figure 3.** Relationship between leaf Ca/Mg and cumulated guava production for harvests cumulated between 2002

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The cumulated fruit yield (2002-2006 harvests) increased quadratically with base saturation of the surface soil layer both in and between rows (Figure 4). Although model maximum goes beyond the values observed in the experiment, it can be inferred that satisfactory cu‐ mulated fruit production can be reached when V is closed to 50% in the rows and 65% be‐

**Figure 4.** Relation between base saturation in the 0-20 cm soil layer, in and between the rows, and cumulated guava

and 2006.

tween the rows.

fruit production from 2002 to 2006.

The graph of the Ca/Mg ratio versus cumulated fruit yield shows, on the other hand, that the lower the ratio, the lower was fruit production (Figure 3).

Leaf Ca and Mg concentrations increased with lime rate and showed quadratic effects

**Figure 2.** Relationships between the leaf concentrations of Ca (a) and Mg (b) and cumulated guava production.

the lower the ratio, the lower was fruit production (Figure 3).

The graph of the Ca/Mg ratio versus cumulated fruit yield shows, on the other hand, that

(Figure 2).

182 Soil Fertility

**Figure 3.** Relationship between leaf Ca/Mg and cumulated guava production for harvests cumulated between 2002 and 2006.

The cumulated fruit yield (2002-2006 harvests) increased quadratically with base saturation of the surface soil layer both in and between rows (Figure 4). Although model maximum goes beyond the values observed in the experiment, it can be inferred that satisfactory cu‐ mulated fruit production can be reached when V is closed to 50% in the rows and 65% be‐ tween the rows.

**Figure 4.** Relation between base saturation in the 0-20 cm soil layer, in and between the rows, and cumulated guava fruit production from 2002 to 2006.

The application of limestone to acidic soils promotes root development and, consequently, the uptake of water and nutrients. Determination of the exchangeable Ca and Mg concentra‐ tion in the soil determined using an exchange resin gives an indication of the potential growth of the root system, especially at planting and tree formation stages and in situations where there are low levels of Ca. In [25], the authors evaluated the effects of liming on root system development and the mineral nutrition of guava trees grown in an acid dystrophic red latosol. They analyzed soil samples taken at four equidistant points 75 cm from the trunks in two layers (0–20 and 20–40 cm depth), in plots that received 0, 3.7 and 7.4 t ha-1 of limestone (reactivity = 94%). The corrective measure was applied before planting, incorpo‐ rated with a disk plow in the 0–30 cm layer and harrowed to level soil surface. Forty-two months after incorporation of the limestone and the third year of guava tree cultivation, the roots were sampled with a cylindrical auger to assess the dry matter and lime content. Lim‐ ing corrected soil acidity, increased base saturation and the availability and absorption of Ca by the plants and promoted root development. Calcium concentrations of 30 mmolc dm-3 in the soil and 7.5 g kg-1 in the roots were associated with greater root growth.

Another popular fruit in Brazil is carambola (*Averrhoa carambola*) or star fruit that also re‐ sponds well to soil acidity correction and fertilization. Investigating three-year old plants in field conditions, [25] found that the accumulation of root dry matter of this *Oxalidaceae* is boosted by limestone application, improving the uptake of nutrients and tree development. Due to the low solubility of limestone, the best practice is to homogeneously incorporate this corrective material down to an adequate depth across the orchard area before planting the seedlings. Indeed, it is not recommended to till the soil after the trees have been planted nor is it advisable to apply limestone in the planting hole, especially along with phosphorus.

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Despite the recognized importance of correcting acidity, there is virtually no study on the re‐ sidual effect of this practice on carambola orchards. The only Brazilian work that assessed the effect of liming on carambola trees [20] was carried out in the country's main producing region between 1999 and 2006. The authors observed that the application of limestone produced sig‐ nificant changes in soil pH, potential acidity (H+Al), sum of exchangeable bases, base satura‐ tion and Ca and Mg concentrations at depths of 0-20, 20-30, 30-40 and 40-60 cm. Besides this, there were linear increases in pH, Ca, Mg, SB and V% and linear decrease of (H+Al) with lime‐ stone rates, both between and in the tree rows at all depths. The greatest changes occurred in

Cumulated carambola fruit production from 2002 to 2006 as function of limestone applica‐ tion is shown in Figure 5. The base saturation between the rows remained higher than under the crown projection throughout the experiment. This behavior was expected because the management the trees required the application of high nitrogen doses which acidify the soil as a result of nitrification [5]. In addition, roots absorbed Ca and Mg and exuded H+

Also, local irrigation was applied, which contributed to changes in the rates of ammonifica‐ tion, nitrification and denitrification. These rates, according to [30], are linked to the availa‐ bility, location and forms of N in the soil profile. This is of fundamental importance in the mobility of nitrogen because of its low binding energy of nitrate to clay minerals and organ‐

**Figure 5.** Relationships between cumulated fruit production from 2002 to 2006 and base saturation in the 0-20 cm

[29].

the layer where the lime had been incorporated (0-30 cm) due to its low mobility.

ic matter [31, 32], leading to nitrate leaching.

soil layer between and within tree rows in a carambola orchard.

Furthermore, liming, by raising the amounts of Ca and Mg in the soil and the plant, can im‐ prove fruit quality. On this crucial point, [26] studied the effects of liming on the quality of guava fruits and observed that this practice did not affect their physical characteristics, such as weight, transverse diameter, length, flesh weight and flesh percentage. However, the ap‐ plication of limestone caused a linear increase in Ca concentrations in leaves and fruits, low‐ ering weight loss of fresh matter and producing firmer fruits when Ca concentrations in the fruits reached at least 0.99 g kg-1. Therefore, the provision for adequate Ca improved fruit quality regarding postharvest longevity.

These beneficial effects of Ca on fruit quality can be explained by the role this element in plant nutrition. In this respect, [27] observed that in guava fruits that received calcium in the form of limestone, cell walls and middle lamellae were well defined and structured, keeping the cells cemented. In contrast, in fruits from the plants not receiving limestone, the cell walls and middle lamellae were destructured and disorganized, respectively. The authors concluded that liming is an effective measure to improve the sub-cellular organization of guava fruits, contributing to tissue integrity.

Studies of the effects of liming on the biometric variables of plants are limited. In [28] the effect of limestone (CaO=45,6%; MgO=10,2% and reactivity=94%) application on trunk diam‐ eter, height and crown volume of Paluma trees was assessed under field conditions. The ex‐ perimental design consisted of random blocks of five treatments and four repetitions. The treatments consisted of rising doses of liming in the 0-30 cm layer as follows: D0 = no lime‐ stone; D1 = half the dose to raise V to 70%; D2 = full dose to raise V to 70%; D3 = 1.5 times the dose to raise V to 70%; and D4 = 2 times the dose to raise V to 70%. Field evaluations were carried out during seven years, starting at orchard's planting in 1999-2000 until the 2005-2006 growing season. The limestone increased trunk diameter and crown volume over the years. These results confirmed the importance of correcting soil acidity and the benefits of applying limestone on the biometric variables of guava trees.

Another popular fruit in Brazil is carambola (*Averrhoa carambola*) or star fruit that also re‐ sponds well to soil acidity correction and fertilization. Investigating three-year old plants in field conditions, [25] found that the accumulation of root dry matter of this *Oxalidaceae* is boosted by limestone application, improving the uptake of nutrients and tree development.

The application of limestone to acidic soils promotes root development and, consequently, the uptake of water and nutrients. Determination of the exchangeable Ca and Mg concentra‐ tion in the soil determined using an exchange resin gives an indication of the potential growth of the root system, especially at planting and tree formation stages and in situations where there are low levels of Ca. In [25], the authors evaluated the effects of liming on root system development and the mineral nutrition of guava trees grown in an acid dystrophic red latosol. They analyzed soil samples taken at four equidistant points 75 cm from the trunks in two layers (0–20 and 20–40 cm depth), in plots that received 0, 3.7 and 7.4 t ha-1 of limestone (reactivity = 94%). The corrective measure was applied before planting, incorpo‐ rated with a disk plow in the 0–30 cm layer and harrowed to level soil surface. Forty-two months after incorporation of the limestone and the third year of guava tree cultivation, the roots were sampled with a cylindrical auger to assess the dry matter and lime content. Lim‐ ing corrected soil acidity, increased base saturation and the availability and absorption of Ca by the plants and promoted root development. Calcium concentrations of 30 mmolc dm-3 in

the soil and 7.5 g kg-1 in the roots were associated with greater root growth.

quality regarding postharvest longevity.

184 Soil Fertility

guava fruits, contributing to tissue integrity.

of applying limestone on the biometric variables of guava trees.

Furthermore, liming, by raising the amounts of Ca and Mg in the soil and the plant, can im‐ prove fruit quality. On this crucial point, [26] studied the effects of liming on the quality of guava fruits and observed that this practice did not affect their physical characteristics, such as weight, transverse diameter, length, flesh weight and flesh percentage. However, the ap‐ plication of limestone caused a linear increase in Ca concentrations in leaves and fruits, low‐ ering weight loss of fresh matter and producing firmer fruits when Ca concentrations in the fruits reached at least 0.99 g kg-1. Therefore, the provision for adequate Ca improved fruit

These beneficial effects of Ca on fruit quality can be explained by the role this element in plant nutrition. In this respect, [27] observed that in guava fruits that received calcium in the form of limestone, cell walls and middle lamellae were well defined and structured, keeping the cells cemented. In contrast, in fruits from the plants not receiving limestone, the cell walls and middle lamellae were destructured and disorganized, respectively. The authors concluded that liming is an effective measure to improve the sub-cellular organization of

Studies of the effects of liming on the biometric variables of plants are limited. In [28] the effect of limestone (CaO=45,6%; MgO=10,2% and reactivity=94%) application on trunk diam‐ eter, height and crown volume of Paluma trees was assessed under field conditions. The ex‐ perimental design consisted of random blocks of five treatments and four repetitions. The treatments consisted of rising doses of liming in the 0-30 cm layer as follows: D0 = no lime‐ stone; D1 = half the dose to raise V to 70%; D2 = full dose to raise V to 70%; D3 = 1.5 times the dose to raise V to 70%; and D4 = 2 times the dose to raise V to 70%. Field evaluations were carried out during seven years, starting at orchard's planting in 1999-2000 until the 2005-2006 growing season. The limestone increased trunk diameter and crown volume over the years. These results confirmed the importance of correcting soil acidity and the benefits

Due to the low solubility of limestone, the best practice is to homogeneously incorporate this corrective material down to an adequate depth across the orchard area before planting the seedlings. Indeed, it is not recommended to till the soil after the trees have been planted nor is it advisable to apply limestone in the planting hole, especially along with phosphorus.

Despite the recognized importance of correcting acidity, there is virtually no study on the re‐ sidual effect of this practice on carambola orchards. The only Brazilian work that assessed the effect of liming on carambola trees [20] was carried out in the country's main producing region between 1999 and 2006. The authors observed that the application of limestone produced sig‐ nificant changes in soil pH, potential acidity (H+Al), sum of exchangeable bases, base satura‐ tion and Ca and Mg concentrations at depths of 0-20, 20-30, 30-40 and 40-60 cm. Besides this, there were linear increases in pH, Ca, Mg, SB and V% and linear decrease of (H+Al) with lime‐ stone rates, both between and in the tree rows at all depths. The greatest changes occurred in the layer where the lime had been incorporated (0-30 cm) due to its low mobility.

Cumulated carambola fruit production from 2002 to 2006 as function of limestone applica‐ tion is shown in Figure 5. The base saturation between the rows remained higher than under the crown projection throughout the experiment. This behavior was expected because the management the trees required the application of high nitrogen doses which acidify the soil as a result of nitrification [5]. In addition, roots absorbed Ca and Mg and exuded H+ [29]. Also, local irrigation was applied, which contributed to changes in the rates of ammonifica‐ tion, nitrification and denitrification. These rates, according to [30], are linked to the availa‐ bility, location and forms of N in the soil profile. This is of fundamental importance in the mobility of nitrogen because of its low binding energy of nitrate to clay minerals and organ‐ ic matter [31, 32], leading to nitrate leaching.

**Figure 5.** Relationships between cumulated fruit production from 2002 to 2006 and base saturation in the 0-20 cm soil layer between and within tree rows in a carambola orchard.

Figure 5 shows accrued fruit production (2002 to 2006 harvests) with rising base saturation in the 0-20 cm soil layer both between and within the rows. Therefore, 78 months after plant‐ ing and acidity correction, maximum fruit production of 121 t ha-1 was obtained in the pH range between 4.6 and 5.0 where the base saturation reached 40% to 53% in and between the rows, respectively, and leaf Ca and Mg levels were 7.6 and 4.0 g.kg-1, respectively [20].

due to the high productive capacity of this species and the high average price of the fruit

In this study, we considered the price per ton of lime applied, divided by sales price per ton of carambola. The most economical dose was calculated based on the derived regression equation between the production of fruit and lime rates applied, making it equal to the ex‐

**Accumulated production Economic dose Increase in fruit yield Cost of limestone Profit Production1**

2002 to 2003 4.5 8.4 0.3 8.1 100 2002 to 2004 4.8 16.0 0.3 15.7 100 2002 to 2005 5.3 28.8 0.3 28.5 100 2002 to 2006 5.3 34.2 0.3 33.9 100

**Table 2.** Economic dose of limestone as function of cumulated production of carambola fruits and limestone cost for

The percentage of fruit production obtained with the most economic lime dosage in relation to the maximum production would be 100%. Therefore, the application of the economic dose allowed savings on limestone without significant loss of production. It is thus realistic to conclude that carambola trees respond positively from an economic standpoint to the ap‐ plication of limestone, which boosts fruit yield up to the dose considered adequate and rec‐

The main carambola growing areas in Brazil are located in regions where soils are acid and show low base saturation which limits the normal development of plants hence orchard pro‐ ductivity. The effect of liming on trunk diameter, crown volume and height of carambola trees was evaluated in an experiment was conducted in the state of São Paulo in a red lato‐ sol (oxisol), in the period from August 1999 to July 2006 [33]. The limestone doses rates were 0, 1.85, 3.71, 5.56 and 7.41 t ha-1. The soil was chemically analyzed and the three biometric variables were assessed during five consecutive harvests. The neutralization of the soil acid‐ ity provided an increase in the biometric variables during the entire experimental period. Liming increased trunk diameter, tree height and crown volume. The nutrients in limestone

The low solubility of most limestones limits the mobility of these materials in the soil profile, requiring initial incorporation to obtain a beneficial effect in the zone exploited by the roots.

1 Percentage of fruit production with the most economic dose in relation to maximum production.

– Ca and Mg – positively influenced the development of the trees.

**6. Liming of established orchards**

**t ha-1 -------- t of fruit per ha ------- %**

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187

on the market.

the 2002-2006 period

ommended by [20].

change ratio, which was 0.05784.

Figure 6 shows differences in cumulated fruit production from 2002 to 2006. As expected, the fruit output rose with years, irrespective of limestone dosage. The reason is that the trees became more productive with the growth in height and leaf area as the study was conduct‐ ed in a new orchard.

**Figure 6.** Cumulated production of carambola fruits related to limestone application rates at planting in 1999.

Figure 7 also shows that the cumulated fruit production increased yearly regardless of lime‐ stone rate. It is important to note that even after seven years, the control plots (zero lime‐ stone) still produced appreciable quantities of fruit, demonstrating the exceptional ability of the carambola tree to develop under adverse conditions.

**Figure 7.** Cumulated carambola fruit production from 2002 to 2006 as function of limestone rates applied in 1999.

In a study of the economic aspects of liming, [22] observed that the cumulated production of carambola fruits as related with the application of different economically feasible rates of limestone coincided with the possible maximum output levels (Table 2). This occurred due to the high productive capacity of this species and the high average price of the fruit on the market.

In this study, we considered the price per ton of lime applied, divided by sales price per ton of carambola. The most economical dose was calculated based on the derived regression equation between the production of fruit and lime rates applied, making it equal to the ex‐ change ratio, which was 0.05784.


1 Percentage of fruit production with the most economic dose in relation to maximum production.

**Table 2.** Economic dose of limestone as function of cumulated production of carambola fruits and limestone cost for the 2002-2006 period

The percentage of fruit production obtained with the most economic lime dosage in relation to the maximum production would be 100%. Therefore, the application of the economic dose allowed savings on limestone without significant loss of production. It is thus realistic to conclude that carambola trees respond positively from an economic standpoint to the ap‐ plication of limestone, which boosts fruit yield up to the dose considered adequate and rec‐ ommended by [20].

The main carambola growing areas in Brazil are located in regions where soils are acid and show low base saturation which limits the normal development of plants hence orchard pro‐ ductivity. The effect of liming on trunk diameter, crown volume and height of carambola trees was evaluated in an experiment was conducted in the state of São Paulo in a red lato‐ sol (oxisol), in the period from August 1999 to July 2006 [33]. The limestone doses rates were 0, 1.85, 3.71, 5.56 and 7.41 t ha-1. The soil was chemically analyzed and the three biometric variables were assessed during five consecutive harvests. The neutralization of the soil acid‐ ity provided an increase in the biometric variables during the entire experimental period. Liming increased trunk diameter, tree height and crown volume. The nutrients in limestone – Ca and Mg – positively influenced the development of the trees.
