Lime-gypsum_GENERAL

Data extracted in April 2021

Note to the reader: This general fiche summarises all the environmental and climate impacts of SOIL AMENDMENT WITH LIME OR GYPSUM found in a systematic review of 7 synthesis research papers [1]. These papers were selected from an initial number of 35 obtained through a systematic literature search strategy, according to the inclusion criteria reported in section 4.

As each synthesis research paper involves a number of primary research papers ranging from 19 to 175, the assessment of impacts relies on a large number of results obtained mainly in field experiments (carried out in situations close to real farming environment), and sometimes in lab experiments or from model simulations.

1. DESCRIPTION OF THE FARMING PRACTICE

Description

Soil amendments are the practices used to improve the soil quality in terms of its structure and biochemical function. Most amendments use calcium-containing minerals, such as lime or gypsum. Both types of amendment have different chemical properties, as explained in Key descriptors.

Key descriptors

Different types of calcium-containing minerals are used in practice, in particular [2]
Lime refers to a material that can come in different forms, especially calcium carbonate (CaCO3) and magnesium carbonate (MgCO3). It is used to reduce soil acidity and to add calcium or magnesium to the soil.
Gypsum, or calcium sulfate dihydrate, (CaSO4 ·2H₂O), is a neutral salt. It can be used to improve soil calcium and sulphur levels. Gypsum is about 200 times more soluble than agricultural lime, allowing it to move readily down the soil profile where it can help to alleviate a range of subsoil problems. In some acid soils, gypsum can be used to ameliorate subsoil aluminium toxicity, while in saline alkaline soils to alleviate sodium toxicity and to regulate soil pH, bulk density and water infiltration.

2. DESCRIPTION OF THE IMPACTS OF THE FARMING PRACTICE ON ENVIRONMENT AND CLIMATE

We reviewed the impacts of soil amendment with lime or gypsum vs. no amendment.

The tables below show the number of synthesis papers reporting positive, negative or no effect, based on the statistical comparison of the intervention and the control. In addition, we include, if any, the number of systematic reviews reporting relevant results but without statistical test of the effects (uncertain). The numbers between parenthesis indicate the number of synthesis papers with a quality score of at least 50%. Details on quality criteria can be found in the methodology section of this WIKI.

Among the 7 synthesis papers, 2 included experiments conducted in Europe and 6 have a quality score higher than 50%. Some synthesis papers reported more than one impact.

Impact	Intervention	Control	Positive	Negative	No effect	Uncertain
Increase carbon sequestration	Gypsum	No gypsum	1 (1)	0	0	0
Increase carbon sequestration	Lime	No lime	0	0	1 (1)	0
Decrease ecotoxicity	Gypsum	No gypsum	0	1 (1)	1 (1)	0
Decrease ecotoxicity	Lime	No lime	1 (1)	0	0	0
Decrease GHG emissions	Lime	No lime	0	0	0	1 (1)
Increase soil biological quality	Gypsum	No gypsum	1 (1)	0	0	0
Increase soil nutrients	Gypsum	No gypsum	0	0	1 (1)	0
Improve soil physico-chemical quality	Gypsum	No gypsum	1 (1)	0	0	0
Improve soil physico-chemical quality	Lime	No lime	2 (2)	0	0	0
Increase crop yield	Gypsum	No gypsum	2 (2)	0	0	1 (0)
Increase crop yield	Lime	No lime	2 (2)	0	0	0

3. DESCRIPTION OF THE KEY FACTORS INFLUENCING THE SIZE OF THE EFFECT

Only the factors explicitly studied in the reviewed synthesis papers with a significant effect are reported below. Details regarding the factors can be found in the summaries of the meta-analyses.

Impact	Factors
Soil physico-chemical quality	Incorporation depth (ref 2), Liming rate (ref 3, 5), Lab/field scale (ref 3, 5), Soil salinity (ref 2), Soil organic matter (ref 5), Soil texture (ref 5), Time scale (ref 5),
Carbon sequestration	Application season (ref 2), Climate (ref 6), Liming duration (ref 6), Soil salinity (ref 2), Soil depth (ref 2)
Ecotoxicity	Liming rate (ref 3), Rice cultivar (ref 3), Lab/field scale (ref 3), Soil Cd concentration (ref 3), Soil texture (ref 3), Soil Zn concentration (ref 3), Type of lime (ref 3)
Crop yield	Aluminium saturation (ref 4), Crop species (ref 4, 5), Incorporation depth (ref 2), Irrigation (ref 2), Ploughing (ref 5), Soil texture (ref 5), Soil pH (ref 1), Water table (ref 2), Water deficiency (ref 4)

4. SYSTEMATIC REVIEW SEARCH STRATEGY 

Keywords 

Search equations WOS 

TOPIC: ("liming" OR "limest*" OR "chalk*" OR "marl*" OR "gypsum") AND TOPIC: (soil) AND TOPIC: ("meta-analy*" OR "systematic* review*" OR "evidence map" OR "global synthesis" OR "evidence synthesis" OR "research synthesis") 

Search equations SCOPUS 

TITLE-ABS-KEY ( ( "liming"  OR  "limest*"  OR  "chalk*"  OR  "marl*"  OR  "gypsum" ) )  AND  TITLE-ABS-KEY ( soil )  AND  TITLE-ABS-KEY ( ( "meta-analy*"  OR  "systematic* review*"  OR  "evidence map"  OR  "global synthesis"  OR  "evidence synthesis"  OR  "research synthesis" ) ) 

Search dates 

No time restrictions 

Databases 

Web of Science and Scopus, run in March 2021 

Selection criteria 

The main criteria that led to the exclusion of a synthesis paper were if the paper: (1) was out of the scope; (2) was not a meta-analysis; (3) was a MA of experimental trials (i.e. no systematic review process); (4) did not deal with soil amendment with lime or gypsum; (5) did not deal with environmental or productivity outcome; (6) did not clearly stated the intervention and comparator treatments; (7) was not written in English. Synthesis papers that passed the relevance criteria were subject to critical appraisal carried out on paper-by-paper basis. 

The systematic search provided 35 synthesis papers (after removing the duplicates) potentially relevant for the practice object of our fiches. From this set of potentially relevant synthesis papers, 7 synthesis papers were selected.

5. LIST OF SYNTHESIS PAPERS INCLUDED IN THE REVIEW

Ref. Num		Authors	Year		Title		Reference			DOI
1	Hijbeek R, van Loon MP, Ouaret W, Boekelo B, van Ittersum MK			2021		Liming agricultural soils in Western Kenya: Can long-term economic and environmental benefits pay off short term investments?		Agricultural Systems 190, 103095	10.1016/j.agsy.2021.103095
2	Wang Y, Wang Z, Liang F, Jing X, Feng W			2021		Application of flue gas desulfurization gypsum improves multiple functions of saline-sodic soils across China.		Chemosphere. 277:130345	10.1016/j.chemosphere.2021.130345
3	Kong L, Guo Z, Peng C, Xiao X, He Y			2021		Factors influencing the effectiveness of liming on cadmium reduction in rice: A meta-analysis and decision tree analysis		Sci Total Environ. 779:146477	10.1016/j.scitotenv.2021.146477
4	Pias, OHD; Tiecher, T; Cherubin, MR; Silva, AGB; Bayer, C			2020		Does gypsum increase crop grain yield on no-tilled acid soils? A meta-analysis		Agronomy Journal 112, 675–692.	10.1002/agj2.20125
5	Li Y.; Cui S.; Chang S.X., Zhang Q.			2019		Liming effects on soil pH and crop yield depend on lime material type, application method and rate, and crop species: a global meta-analysis. Journal of Soils and Sediments 19(4)		J Soils Sediments 19:1393–406	10.1007/s11368-018-2120-2
6	Eze, S; Palmer, SM; Chapman, PJ.			2018		Soil organic carbon stock in grasslands: Effects of inorganic fertilizers, liming and grazing in different climate settings		Journal of Environmental Management 223, 74-84	10.1016/j.jenvman.2018.06.013
7	Tiecher, T; Pias, OHD; Bayer, C; Martins, AP; Denardin, LGD; Anghinoni, I			2018		Crop Response to Gypsum Application to Subtropical Soils Under No-Till in Brazil: a Systematic Review		Revista Brasileira de Ciencia do Solo 42:170025	10.1590/18069657rbcs20170025

^[1] Synthesis research papers include either meta-analysis or systematic reviews with quantitative results.

^[2] References used:

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2. DESCRIPTION OF THE IMPACTS OF THE FARMING PRACTICE ON ENVIRONMENT AND CLIMATE

4. SYSTEMATIC REVIEW SEARCH STRATEGY

5. LIST OF SYNTHESIS PAPERS INCLUDED IN THE REVIEW