Presented study documents the effects of experimental liming on the forest soils and forest plantations (Norway spruce). Liming was performed in the top part of the Orlicke hory Mts., in the altitude 1100 m. Results documented mutual effects on the forest soil as well as on the newly established Norway spruce plantations. It was evaluated the effect of liming on the soil pH, soil adsorption complex, exchangeable nutrients. Special attention was paid to the nitrogen dynamics and to the plantation growth and nutrition

The contribution summarizes outputs of annual measurements that were made in the eleven-year long period of observation (1991-2001). In this case, the liming had markedly positive effect on prosperity of spruce plantation up to now. The limed variants "surface" and "planting pit" show lower values of the total mortality than the control variant. Furthemore, the mean value of the periodic annual increment of the trees of the control variant is clearly lower than the mean values of the variant "surface" and the variant "planting pit". According to soil analyses the above described forms of liming do not seem to induce any serious negative changes within soil in this case

Representing the staple crop for half of the world population, rice can accumulate high levels of cadmium (Cd) in its grain, posing concerns on food safety. Different soil amendments have been proposed to decrease Cd accumulation in rice grain by either decreasing soil Cd availability, introducing competitive ions on Cd uptake, or down-regulating the expression of transporters for Cd uptake. However, the effectiveness of soil amendments applied alone or in combinations needs to be tested under field conditions. Here, we present results of field trials with two rice cultivars differing in Cd accumulation grown at three field sites in southern China in two years, to investigate the effects of two Mn-containing soil amendments (MnO₂, Mn-loaded biochar (MB)), Si fertilizer (Si), limestone, and K₂SO₄, as well as interactions among MnO₂, Si, and limestone on decreasing Cd accumulation in rice grain. We found that single applications of MnO₂ or MB to acidic soils low in Mn decreased grain Cd concentrations by 44–53 % or 78–82 %, respectively, over two years without decrease in performance. These effects were comparable to or greater than those induced by limestone liming alone (45–62 %). Strong interactions between MnO₂ and limestone resulting from their influence on soil extractable Cd and Mn led to non-additive effects on lowering grain Cd. MB addition minimized grain Cd concentrations, primarily by increasing extractable and dissolved Mn concentrations, but also by decreasing Cd extractability in soil. In comparison, Si and K₂SO₄ amendments affected grain Cd levels only weakly. We conclude that the amendments that decrease labile Cd and increase labile Mn in soils are most effective at reducing Cd accumulation in rice grain, thus contributing to food safety.

Present study reports the laboratory and field scale application of different organic and inorganic amendments to immobilize cadmium (Cd) and lead (Pb) in a co-contaminated alluvial paddy soil. For that purpose, lime, biochar, Fe-biochar and two composite amendments (CA) composed of biochar, lime, sepiolite and zeolite (CA1: composite amendment 1) and manure, lime and sepiolite (CA2: composite amendment 2) were firstly tested in an incubation experiment to ameliorate Cd and Pb co-contaminated alluvial soil. It was observed that liming and CA2 elevated the soil pH and reduced DTPA extractable Cd and Pb in the incubated soil leading to higher metal immobilization. Therefore, efficiency of lime and CA2 was further investigated in field conditions with mid rice as the test crop to evaluate field scale immobilization and precise application rate for the tested soil type. DTPA and CaCl₂ extractable Cd (46 and 51%) and Pb (68 and 70%) in field soil were decreased with applied treatments. Speciation of Cd and Pb also promoted conversion of metal exchangeable contents to less-available forms. Activated functional groups on amendments’ surface (_OH bonding, C_O and CO, -O-H, Si–O–Si, carboxylic and ester groups) sequestered metals by precipitation, adsorption, ion exchange or electro static attributes. Application of lime at 2400 kg/acre (T4) and CA2 at 1200 kg/acre was more effective in reducing rice shoot and grains metal contents. Moreover, obtained results in terms of pH, extractable content, speciation and yield, and microanalysis of amendments highlights the remarkable efficiency of lime and composite amendment to sorb Cd and Pb providing the key evidence of these amendments for metals immobilization and environmental remediation. Considering these results, lime and CA2 are potential amendments for co-contaminated rice field especially in context of alluvial soil.

Liming is a safe and effective remediation practice for Cd contaminated acid paddy soil. The fate of Cd can also be strongly influenced by redox chemistry of sulfur. But it is unclear if, to what extent and how the combination of liming and sulfur mediation could further control Cd uptake by paddy rice. A rice cultivation pot experiment was conducted to evaluate the impact of different sulfur forms (S⁰ and SO₄²⁻ in K₂SO₄) on the solubility, uptake and accumulation of Cd in the soil-paddy rice system and how liming and reducing organic carbon mediate the process. Results showed that under neutral soil circumstances achieved by liming, co-application of K₂SO₄ and glucose significantly reduced brown rice Cd by 33%, compared to liming alone. They made it more readily for Cd²⁺ to be precipitated into CdS/CdS₂ or co-precipitate with newly formed FeS/FeS₂/iron oxides. The higher pH balancing capability of K₂SO₄ as well as liming kept the newly formed sulfide or iron containing minerals negatively charged to be more prone to adsorb Cd²⁺, that kept the porewater Cd²⁺ the lowest among all the treatments. Individual K₂SO₄ showed significant promoting effect on soil Cd solubility due to SO₄²⁻ chelation effect. Furthermore, K₂SO₄ had much weaker inhibiting effect on Cd translocation from root to grain, it showed no significant attenuating effect on brown rice Cd. S⁰ containing treatments displayed weaker or no attenuating effect on brown rice Cd due to its strong soil acidification effect. On the basis of liming, organic carbon induced sulfur (K₂SO₄) mediation showed great application potential for safe production on large areas of acid paddy soil contaminated by Cd.

Rapid industrialization in China during the last three decades has resulted in widespread contamination of Cd in agricultural soils. A considerable proportion of the rice grain grown in some areas of southern China has Cd concentrations exceeding the Chinese food limit, raising widespread concern regarding food safety. In this review, we summarize rice grain Cd concentrations in national Chinese markets and in field surveys from contaminated areas, and analyze the potential health risk associated with increased dietary Cd intake. For subsistence rice farmers living in some contaminated areas of southern China who mainly consume locally-produced Cd-contaminated rice, their estimated dietary Cd intake is now comparable to that for the population in the region of Japan where the Itai-Itai disease was first reported. Interventions must be taken urgently to reduce Cd intake for these farmers. We also analyze i) the main reasons causing elevated grain Cd concentrations in southern China, ii) the dominant biogeochemical processes controlling the solubility of Cd in paddy soils, and iii) molecular mechanisms for the uptake and translocation of Cd in rice plants. Based on these analyses, we propose a number of countermeasures to address soil Cd contamination, including i) mitigation of Cd transfer from paddy soils to rice grain, and ii) intervention in those farmers who consume home-grown Cd-contaminated rice. Liming to increase soil pH to 6.5 and gene editing biotechnology are effective strategies to decrease Cd accumulation in rice grain. For these local farmers with high-Cd exposure risk, local governments should monitor the Cd concentration in their home-grown rice and exchange those high-Cd rice with low-Cd rice in order to reduce their dietary Cd intake.

Keeping in view the expanding environmental pollution and irrigation water deficit, a pot experiment was performed for the upland (Huyou2, Hanyou737) and paddy rice cultivars (Taigeng8; Yixiang2292), to study soil liming effects on methane (CH₄) and nitrous oxide (N₂O) emission, bioavailability and accumulation of Cd, Pb in upland and paddy rice. Upland rice reduced 90% of soil CH₄ emission as compared to paddy conditions. Soil CH₄ emission decreased by 45% and 39% with dolomite, and it reduced by 35% and 33% with lime treatment both in upland and paddy conditions, respectively. Soil N₂O emission decreased by 44% and 52% with dolomite, and with the lime application, it was reduced by 37% and 44% for both upland and paddy conditions respectively. Reduction in soil DTPA-extractable Cd was between 37-53% and 43–80% with dolomite and 16–37% and 24–72% Cd decreased with lime application in upland and paddy conditions respectively. Soil DTPA-extractable Pb reduced by 27–44% and 25–53% with dolomite and 16–40% and 11–42% with soil-applied lime in upland and paddy conditions, respectively. Cd accumulation in rice grain was decreased by 47–88% and 62–79% with dolomite and 31–86% and 45–52% reduction by lime application in upland and paddy rice respectively. Rice grain Pb reduced by 58–91% and 66–78% with dolomite application and 32–71% and 44–71% with lime in upland and paddy rice, respectively. Our results showed that soil liming significantly reduced soil N₂O and CH₄ emission and Cd, Pb accumulation in rice grain, but dolomite was more effective as compared to lime. Altogether, results of this study suggest that upland rice can be cultivated in CdPb polluted soils with least soil CH₄ emission. Cd and Pb toxicity, accumulation, and N₂O emission in upland rice can be minimized by soil liming of 3 g kg⁻¹ and optimizing the nutrients composition of the soil.

A pollutant accumulation model (PAM) based on the mass balance theory was developed to simulate long-term changes of heavy metal concentrations in soil. When combined with Monte Carlo simulation, the model can predict the probability distributions of heavy metals in a soil–water–plant system with fluctuating environmental parameters and inputs from multiple pathways. The model was used for evaluating different remediation measures to deal with Cd contamination of paddy soils in Youxian county (Hunan province), China, under five scenarios, namely the default scenario (A), not returning paddy straw to the soil (B), reducing the deposition of Cd (C), liming (D), and integrating several remediation measures (E). The model predicted that the Cd contents of soil can lowered significantly by (B) and those of the plants by (D). However, in the long run, (D) will increase soil Cd. The concentrations of Cd in both soils and rice grains can be effectively reduced by (E), although it will take decades of effort. The history of Cd pollution and the major causes of Cd accumulation in soil were studied by means of sensitivity analysis and retrospective simulation.