Low Calcareous Soil Research Articles

Growing media effect on essential and non-essential mineral composition of lettuce

The composition of the environment in which vegetables are grown or their interaction with the applied fertilizer or nutrient solution determines the essential and non-essential element contents of the vegetables. The main purpose of this study is to evaluate variations of essential and non-essential mineral concentrations of lettuce plants (Lactuca sativa L. cv. Sementel) grown under soil and soilless media. The plants were grown in: low calcareous soil (LCS) and high calcareous soil (HCS), or rockwool or cocopeat. The best growth was from plants grown in cocopeat followed by rockwool, LCS, and HCS. Nitrogen, P, and Zn concentrations of rockwool and cocopeat grown plants were higher than in plants grown in the soils. The Ca, Ti, Sr, Al, Zr, and Ba concentrations of soilless grown plants was lower than that of soil-grown plants. Potassium and S concentrations of lettuce plants were higher in HCS, rockwool or cocopeat than for plants grown in LCS. The Mg and Mn concentrations were highest in plants in cocopeat and LCS. Copper concentration of lettuce plants was highest in HCS. Growing media had no effect on Co, As, Pb, W, Hg, Cr, Nb, Cd, In, I, Cs, Ta, Th, Ga, and Ce concentrations. Concentrations of Br, Rb, V, Se was highest in HCS, cocopeat, HCS, LCS and rockwool, respectively. In conclusion, essential element contents and the growth of lettuce plants was better in cocopeat and rockwool medium than the soils. Zirconium, Ba, Ni, Rb, Al and Ti that are not necessary for plants and humans are lower in the lettuce plants growing in rockwool and cocopeat. According to these results, vegetables grown without soil should be considered as an important advantage for human health.

Distribution of Boron in Different Fractions in Some Alkaline Calcareous Soils

Distribution of boron (B) in different fractions is still not well defined when it is applied in B-deficient alkaline calcareous soil and after harvesting of the sown crop. In the present greenhouse experiment with green gram crop, three B-deficient soils with calcium carbonate contents of 0.8 (S I), 2.1 (S II), and 4.6 (S III) percent were collected from different sites in Ludhiana and Bhatinda Districts, Punjab, India. The treatments composed of five levels of soil-applied B (0, 0.5, 0.75, 1.0, and 1.5 mg B kg−1) soil and the experiment was laid out in Completely Randomized Design (CRD) factorial design with three replications. Mean readily soluble, specifically adsorbed, and oxide-bound B fractions got increased significantly with increase in B applications. Distribution of readily soluble B was more in low calcareous soil than in high calcareous soil. Mean values of specifically adsorbed, oxide-bound, residual, and total B were significantly more in high calcareous soils as compared to low calcareous soils. At maturity, specifically adsorbed B converted into other fractions to maintain equilibrium in soil solution. Organically bound B was greater than the oxide-bound B fraction. Among all fractions, residual fraction accounted for the major portion of the total B. Available B was negatively and significantly correlated with calcium carbonate (CaCO3) content of soil (r = −0.99*). At the same time, specifically bound B was also negatively and significantly correlated with readily soluble B (r = −0.99*) whereas organically bound B was positively correlated with organic carbon content of soil (r = −0.99*).

Effect of wheat root exudates on mobilization of iron and zinc from calcareous soils

To study the influence of phytosiderophores (PS) released from some Egyptian wheat cultivars on mobilization and absorption of iron (Fe) and zinc (Zn) from pre‐amended calcareous soils, three selected wheat cultivars (Sids 10, Giza 162, and Baniswaif 2) were used. The cultivars were pre‐cultured for 17 days in nylon bags as the control root compartment (RC) and filled with fine sand and provided with nutrient solution +/‐ Fe‐EDTA. The nylon bags with roots of the seedlings were brought in contact for further 4 days with pre‐amended calcareous soils. DTPA‐extractable Fe and Zn from amended calcareous soils with sludge was much higher than from untreated soils. Relative increases in extractable Fe or Zn were found in Fe‐deficient wheat (‐Fe pretreatment) compared with Fe‐sufficient plants. The extractable amounts of Fe‐ and Zn‐DTPA from different calcareous soils were affected by the distance from the central root compartment where minimum values were reached at distance of more than 4 mm. Release of PS and mobilization of Fe and Zn were highest with, Sids 10 and Baniswaif 2 cultivare while Giza 162 was lower particularly under sufficient seedlings. Moreover, increasing CaCO3 content in calcareous soils minimized the growth differences among wheat cultivars. The status of Fe and Zn contents was improved in roots compared with shoots during the 4‐day growth period. Furthermore, nutrient status was generally higher in soils amended with sludge compared with untreated soils. Sids 10 have the highest values of Fe content particularly under Fe‐deficient conditions while Giza 162 was inferior. Zinc content in Sids 10 was superior in high calcareous soil (53% CaCO3 content) while Baniswaif 2 was superior in low calcareous soil (14% CaCO3 content).

Growth and mineral nutrition of pear rootstocks in lime soils

Little information is available on the tolerance of pear rootstocks to lime-induced iron chlorosis. In a 2-year study, micropropagated plants of the pear rootstocks OH × F 51, OH × F 333, B 21, C 106 and D 50, and Adams quince were grown in low calcareous soil (LC, 1.6% lime) and high calcareous soil (HC, 72.9% lime) as well as in a mixture of HC:LC (50:50, w:w) (M1) at 33.8% lime content and a mixture of HC:LC (75:25, w:w) (M2) at 48.3% lime content. By the end of Year 2, OH × F 51, B 21 and C 106 had reduced dry matter accumulation in stem and roots in HC soil only; the other rootstocks were adversely affected by lower soil-lime contents. Only Adams decreased the shoot-to-root dry weight ratio in relation to increased soil lime. Leaf chlorotic symptoms of plants grown under increasing lime were most severe in OH × F 333, D 50 and Adams. Root Ca concentration increased linearly and root iron and manganese decreased linearly at increasing soil lime rates. Root Cu concentration increased linearly with soil Cu content, the latter being ten-fold higher in HC than LC soil. These findings indicate varying susceptibility of pear rootstocks to lime-induced iron chlorosis. Rootstock tolerance is a necessary condition in order to overcome lime-induced iron chlorosis in pear cultivars. In grafted trees it is, however, possible that mechanisms other than iron uptake are involved in leaf chlorosis.