**6. Liming of established orchards**

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].

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‐

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

the carambola tree to develop under adverse conditions.

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

**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

ed in a new orchard.

186 Soil Fertility

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. In fruit orchards already in production, the procedure recommended by the official bulletins in Brazil is light incorporation of limestone in the tree rows [10]. However, it is probable that this recommendation would change if there were more research findings, considering the various phytosanitary problems that can occur due to lime incorporation, such as injuries and reduction of volume of the roots, with consequent risk of infections, dissemination of diseases in the orchard, increased attack by pests, especially mites, cochineals [34] and nem‐ atodes [35], as well as soil destructuring and compaction.

reaction upon liming occurred 12 to 18 months after lime application. Plants' nutritional sta‐ tus and fruit yield were significantly improved?. Cumulated production indicated that the ideal base saturation for orange trees was close to 50%. In the same experiment, [40] as‐ sessed the effect of limestone on the leaf Mn content. They found significant decreases in Mn levels with limestone additions. There was a high correlation between base saturation in the 10-20 cm soil layer and leaf Mn levels. Maximum fruit yields were associated with leaf con‐ centrations between 33 and 70 mg Mn kg-1. Another liming experiment allowed determin‐ ing, by the Compositional Nutrient Diagnosis (CND), the Diagnosis and Recommendation Integrated System (DRIS) and the mathematical chance methods, the adequate nutrient

Despite still insufficient scientific basis, practical experience showed that the pH, and conse‐ quently base saturation, should not be allowed to decline drastically in established orchards. The reason is that it is very hard to correct high acidity in the soil layers down to depths exploited by adult trees within a reasonable time interval. The best strategy in these situa‐ tions is to apply small amounts of finely ground limestone annually (example.g, 1 ton ha-1), hence correcting acidity gradually, to avoid any sharp rise in acidity. It is clear, however, that soil analysis continues to be essential to assess the best timing and rates to apply lime at

Soil acidity is a determinant factor limiting crop production in tropical areas. Fruit crops are perennials that exploit the same volume of soils during of time. As a result, soil acidi‐ ty correction must be sustained in the roo zone to avoid aluminium toxicity and supply adequate amounts of calcium and magnesium to the crop. Research results show the eco‐ nomic advantages of liming to correct soil acidity and thus improve fruit yield and quali‐

1 Unesp, Universidade Estadual Paulista, Campus Jaboticabal, Via de Acesso Paulo D.

3 ERSAM, Department of Soils and Agrifood Engineering, Université Laval, Quebec (Qc),

2 Unesp, Universidade Estadual Paulista, Campus Registro, Registro, São Paulo, Brazil

, Serge-Étienne Parent3

and Léon Etienne Parent3

Soil Acidity and Liming in Tropical Fruit Orchards

http://dx.doi.org/10.5772/53345

189

ranges to obtain high yield in Pêra orange groves [41].

, Danilo Eduardo Rozane2

\*Address all correspondence to: natale@fcav.unesp.br

Donato Castelane, Jaboticabal, São Paulo, Brazil

the surface without incorporation.

**7. Conclusions**

ty in Brazilian orchards.

**Author details**

William Natale1

Canada

In orchards with adult trees, the application of limestone at the surface, without incorporation, will gradually neutralize the acidity below the surface due to the movement of the particles through the profile, at a rate of 1 to 2 cm a year, if moisture and drainage conditions are suitable [36]. Therefore, surface liming, even though possible, requires time to produce beneficial ef‐ fects. However, the information mentioned above was obtained under edaphoclimatic condi‐ tions different than the tropics. Other studies have shown that it is possible to apply limestone at soil surface without incorporation and obtained satisfactory results over time.

To assess the effect of surface liming on soil fertility, plant nutrition and the productivity of guava trees, an experiment was conducted in a commercial orchard grown on a red-yellow Argisol (Ultisol) in the main guava producing region of the state of São Paulo [37]. The randomized block design was a 2 x 5 factorial scheme with three repetitions, where the fac‐ tors were two types of limestone (common, with PRNT=80%; and calcined, with PRNT=131%), applied at five rates (0, 0.5, 1, 1.5 and 2 times the recommended rate to raise base saturation to 70%) without incorporation. The results showed that surface liming with either common or calcined limestone reduced soil acidity in proportion to lime rate down to depths of 0-10 and 10-20 in the established guava orchard. In the 10-20 cm layer acidity de‐ clined 6 to 12 months after applying calcined limestone and 24 months after the application of common limestone. The chemical composition of the leaves and fruits and fruit yield were not influenced by the lime treatments. The authors attributed this to the fact that be‐ cause the trees are perennial, they need time to respond to change in management. They concluded that it is possible to surface lime established guava orchards to correct soil acidity both in surface and lower layers. However, there is a need for further research to determine the specific criteria for this crop and for adjusting the rates to the optimum base saturation for this type of liming.

Orange (*Citrus sinensis*) growing is another important activity in Brazil, occupying some 850 000 hectares. Brazil is the top producer of oranges accounting for 25% of world's total pro‐ duction and is the world's leading exporter of orange juice. This means that of each five cup of orange juice consumed in the world, three come from Brazilian orchards [38]. A field ex‐ periment was conducted in a grove of adult orange trees (Pêra variety) established on a red latosol (oxisol) with five rates of calcined limestone (PRNT=131%) applied onto soil surface without incorporation [39]. Treatment effects were monitored for three consecutive years on the movement of the lime through the profile 6, 12, 18, 24, 30 and 36 months after applica‐ tion, on the chemical properties of the soil, on plant nutritional status and on fruit yield. Sur‐ face application of calcined limestone altered the base saturation as well as the soil chemistry in the three successive soil layers (0-10, 10-20 and 20-40 cm). The maximum soil reaction upon liming occurred 12 to 18 months after lime application. Plants' nutritional sta‐ tus and fruit yield were significantly improved?. Cumulated production indicated that the ideal base saturation for orange trees was close to 50%. In the same experiment, [40] as‐ sessed the effect of limestone on the leaf Mn content. They found significant decreases in Mn levels with limestone additions. There was a high correlation between base saturation in the 10-20 cm soil layer and leaf Mn levels. Maximum fruit yields were associated with leaf con‐ centrations between 33 and 70 mg Mn kg-1. Another liming experiment allowed determin‐ ing, by the Compositional Nutrient Diagnosis (CND), the Diagnosis and Recommendation Integrated System (DRIS) and the mathematical chance methods, the adequate nutrient ranges to obtain high yield in Pêra orange groves [41].

Despite still insufficient scientific basis, practical experience showed that the pH, and conse‐ quently base saturation, should not be allowed to decline drastically in established orchards. The reason is that it is very hard to correct high acidity in the soil layers down to depths exploited by adult trees within a reasonable time interval. The best strategy in these situa‐ tions is to apply small amounts of finely ground limestone annually (example.g, 1 ton ha-1), hence correcting acidity gradually, to avoid any sharp rise in acidity. It is clear, however, that soil analysis continues to be essential to assess the best timing and rates to apply lime at the surface without incorporation.
