Written evidence submitted by Canterbury Christ Church University (SH0097) to the House of Commons Environment, Food and Rural Affairs Committee on Soil health. First Report of Session 2023–24, HC 245.

Executive summary Soils are fundamental to ecosystem functioning in agricultural soils and therefore their ability to provide public goods. Agri-environment policy measure progress towards improving soil health through various physio-chemical or biological means; however, these are no longer fit for purpose. This paper is split into two sections: soil health indicators, covering physio-chemical characteristics and biodiversity, and soil contamination, dealing with heavy metals, pharmaceuticals and microplastics. Within this document, we make a series of recommendations to improve monitoring and subsidy schemes under the new Environmental Land Management schemes. New policy frameworks also need to consider known and emerging contaminants if they are to be a true representation of the health of our soils. Recommendations are given below, split into: physio-chemical characteristics, biodiversity, heavy metals, pharmaceuticals and microplastics. Physio-chemical indicators: 1. Expand on the soil health indicators quantified under the ELMS to include several more that are mentioned under the Countryside Survey (i.e. pH, bulk density, soil carbon, organic matter, total nitrogen, mineralizable nitrogen and total phosphorous), and offer a set of relevant tests related to soil health, taking into account basic soil characteristics, cropping systems and/or climate. 2. Subsidise costs of soil testing under the ELMS so that farmers can collect good quality data on soil health before and after management interventions to demonstrate if soil health has been improved. 3. Ensure that all tests have a standardised method for soil sampling, storage and testing to enable comparisons and accurately track long-term changes. 4. There is a risk of low farmer participation due to the loosely defined soil assessment methods. There is a need for clear guidance and defined, but easy to use, methodologies and farmers need to have access to expert advice and guidance. 5. Soil quality indicators should be relatable to a specific ecosystem services/public goods, and farmers need clear guidance on how to interpret the results of their soil tests in this context. 6. Conduct a large-scale monitoring scheme to provide a reference dataset for farmers to compare their soil physio-chemical data to, or create a scoring system that is easy for farmers to interpret to use as a comparison or demonstrate changes in soil health. Biological indicators: 1. Any agreements attaching subsidy payments to improvements in soil biodiversity need to be long-term and might need to include staged and proxy payments. This is to account for the longer timeframe that soil communities may take to respond to new land management approaches compared to physio-chemical characteristics. 2. Current measurements of biological health are no longer appropriate. Since soil biodiversity – especially microbial biodiversity – drives soil functioning and is a key component of soil health, this needs to be included as a soil health indicator under the new ELMS. 3. Although methods for biodiversity assessment using metagenomics are complex, schemes ot monitor soil must be cooperative. Thus, farmers have to be able to on collecting soil samples and sending these for analysis. Similarly, the biodiversity data that is sent back to the farmer also needs to be easily interpreted (i.e. using a simple summary of findings or scoring system). Heavy metals: 1. Expand on heavy metals that are used as soil health indicators under the Countryside Survey (total copper, zinc, cadmium, and nickel) to include several more that are prevalent in agricultural soils. 2. Include contamination as a soil threat and add Action(s) within the ELMS that targets remediation of contaminated soils. Pharmaceuticals: 1. First, there is a need for prioritization: there are more than 1,900 active pharmaceutical compounds in use, making it a challenge to study all of them at once. Prioritization will allow identifying those compounds that can pose the greatest risk to the UK soil, plants, environment, and public health. 2. Soil microbiome is diverse and varies with location, soil type, plants, environmental conditions, and human activities. There is a need to understand the effect of prioritized CECs pharmaceuticals on soil microbiome and its interaction with the rhizosphere in different agroecological zones of the UK. 3. How the presence of prioritized CECs in the soil affects the growth, productivity, and nutritional quality of main UK crops needs to be assessed. This will be achieved by evaluating the mechanisms of absorption, plant uptake and metabolism of CECs in main UK crop species. 4. With the anticipated negative effects of the CECs on agriculture and the environment, strategies for the remediation of prioritized CECs from contaminated soils should be developed. Different available bioremediation approaches need to be tested to identify those who would work on those CECs and in the UK context. 5. Considering the current development of climate change and its impact on agriculture, it is inevitable to assess how climate change is affecting / will affect the prioritized CECs in their interaction with plants and soil. Microplastics: 1. Define ‘microplastics’ clearly as an environmental contaminant in policy documents. 2. More accurate estimates of deliberate and accidental release of plastics are required to reduce uncertainty in approximations of the quantity of plastics entering soils. 3. Well-aligned initiatives, best management practices, more stringent policies and co-operative efforts of the public, manufacturers and government officials are urgently needed to reduce illegal disposal of plastic waste, moderate improper use of plastic products in the agriculture and increase the proportion of plastics undergoing waste management or recycling processes. 4. Better characterisation of MPs (i.e. origin, shape, size, and composition) and evaluation of their in soils (i.e. distribution, transport and degradation) is required, with reference to specific soil characteristics, agricultural systems and climates. 5. Understand how the presence of MPs in the soil affects soil biota and the growth, productivity and nutritional quality of crops, and determine soil guideline values for MPs in soils. 6. Develop a standard set of low-cost, high-efficiency protocols to collect and process soil samples, and then to isolate, identify and quantify microplastics in soils, depending on both the soil characteristics and the type of MPs being quantified

Evaluation of 99 pesticide residues in major agricultural products from the Western Highlands zone of Cameroon using QuECHERS method extraction and LC-MS/MS and GC-ECD analyses

There is no information available on pesticide residue levels in major food commodities harvested in Cameroon, especially from the western highlands region, the food basket of the country. Hence, this study evaluated the residues of 99 pesticides in 72 samples of 12 agricultural products collected in the region, using QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method extraction, and analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) and gas chromatography with electron capture detection (GC-ECD). This method was suitable for detecting the targeted compounds: For 81 pesticides by LC-MS/MS, the limit of quantification (LOQ) was between 0.0004 and 0.0537 mg/kg; and for 18 halogenated pesticides by GC-ECD, it ranged from 0.0012 to 0.2180 mg/kg. The residues of 62 pesticides, including 12 banned compounds, were found in the samples. Insecticides (39.7%) were the most prevalent group, with all the samples containing at least one pesticide. Twenty-one pesticides (34.4%) exceeded their European Union maximum residue limits (MRLs) and 22 pesticides (34.4%) were found in all 6 sampling locations. Malathion and p,p′-DDT were the most distributed pesticides, found in almost all the samples and sampling sites. Food items with the highest rates of positive results were chili pepper (23.2%), white pepper (20.2%), kidney beans (17.3%), and soybeans (17.2%). Samples with residues above their MRLs represented 38% of all the positive analyses; chili pepper (6.4%) and kidney beans (5.5%) were found to have the most residues above their MRLs. The most critical food commodities were kidney beans, soybeans, chili pepper, and maize. This data presents scientific evidence that investigation into continuous monitoring and good regulation of pesticide usage in Cameroon is needed, and paves the way for health risks analysi

Storage of fruits and vegetables in refrigerator increases their phenolic acids but decreases the total phenolics, anthocyanins and Vitamin C with subsequent loss of their antioxidant capacity

It is of paramount importance for consumers, scientists and industrialists to understand how low-temperature storage of food items affects their bioactive compounds and properties. This study evaluated the effects of cold storage on total phenolics (TP), phenolic acids profile (PA), total anthocyanins (TA), total ascorbic acid (Vit. C) and antioxidant activity (AA) of 19 fruits and vegetables, collected from local Indian markets and stored in refrigerator (4 °C) during 15 days. Content of TP was highest in dill and amaranth and decreased (up to 29.67%) with storage. Leafy vegetables (amaranth, dill, onion, fenugreek and spinach) contained higher amounts of the 12 PA revealed by UPLC-UV; ellagic, gallic, sinapic and vanillic acids levels were the highest; chlorogenic acid (ρ = 0.423), syringic acid (ρ = 0.403) and sinapic acid (ρ = 0.452) mostly correlated with TP; and the PA increased during storage. Highest contents of Vit C estimated by AOAC, DCPIP and DNP methods were found in amaranth, dill and pomegranate, and decreased with storage. Pomegranate showed highest TA levels and low-temperature storage did not significantly increase TA, which was the largest contributor of TP in fruits and vegetables (ρ = 0.661). Storage induced a drastic decrease of AA, which mostly correlated with TP (ρ = 0.808, 0.690 and 0.458 for DPPH, ABTS and FRAP assays, respectively). Spearman’s correlation confirmed by principal component analysis demonstrated that dill, pomegranate and amaranth had the highest overall antioxidant capacity, whereas orange juice and carrot showed the lowest. The results provide support for a key-role of TP, followed by Vit. C and TA in antioxidant capacity of fruits and vegetables, which could be interesting dietary sources of natural antioxidants for prevention of diseases caused by oxidative stress

Antifungal potential of essential oils, aqueous and ethanol extracts of thirteen plants against Fusarium oxysporum f . sp Lycopersici and Phytophtora infestans (Mont.) de Bary as major tomato pathogens

Antifungal activity of essential oils (EO), ethanol extracts (ETE) and cold water extracts (CWE) of thirteen plants was evaluated against Fusarium oxysporum and Phytophtora infestans causal agents of tomato Fusarium wilt and late blight diseases respectively. The supplemented media and slide germination techniques were carried out to determine the effect of extracts on the mycelial growth and conidia germination of pathogens. The results showed that essential oils exhibited the highest antifungal activity followed by ETE and CWE. Callistemon citrinus, Cymbopogon citratus and Ocimum gratissimum essential oils were the most active inhibiting completely radial growth and conidia germination of Phytophtora infestans at 312.5 and 625 µg/ml. Essential oils of Ocimum gratissimum and Cymbopogon citratus inhibited totally the radial growth and conidia germination of Fusarium oxysporum at 625 and 312.5 µg/ml respectively. ETE of Ageratum conyzoides and Callistemon citrinus were the most active inhibiting radial growth of Phytophtora infestans. Cymbopogon citratus and Ocimum gratissimum were the most active against radial growth and conidia germination of Fusarium oxysporum at 6250 µg/ml. The fungi toxic potential of some extracts was comparable to synthetic fungicides used as positive controls. Preliminary phytochemical analysis of ETE and CWE revealed that stronger inhibiting effects were recorded with extracts rich in phenols, flavonoids, tannins, and coumarins. These findings may contribute to develop new green fungicides to protect tomato from Fusarium wilt and late blight diseases

Molecular characterization of Indian potato (Solanum tuberosum L.) varieties for cold-induced sweetening using SSR markers

Cold-induced sweetening developed during storage of potatoes (Solanum tuberosum L.) at low temperature is a crucial factor influencing the processing quality of potato tubers and remains one of the principal concerns of potato processing industry. Developing CIS-resistant genotypes is the most effective method to cope with this stress. In this study, the genetic diversity of 11 Indian potato varieties with different reactions to CIS was assessed using 10 SSR primers. The primers detected a total of 42 alleles arranged in 44 different configurations, among which 37 alleles (88%) were polymorphic. The polymorphic information content (PIC) value of the SSR locus ranged from 0.473 to 0.787 thus indicating a high utility of these markers for study of genetic diversity in potato. A number of polymorphic fragments appeared to be specific to a given sugar-forming group. Primer Sti007 generated one fragment Sti007131bp present only in all the high sugar-forming varieties. The dendrogram derived from Dice’s similarity coefficients among the 11 varieties could partially but efficiently differentiate close parents and sugar-forming groups among the varieties. These findings demonstrate the effectiveness of SSR markers to assess the genetic variation among potato cultivars in order to develop molecular markers associated with CIS to improve potato breeding programs

Antifungal potential of extracts from four plants against Acremonium apii and Colletotrichum dematium, two major pathogens of celery (Apium graveolens L.) in Cameroon

In order to contribute to a sustainable control of plant diseases through the use of natural compounds, the antifungal potential of 11 extracts from 4 Cameroonian plants (Ageratum conyzoides, Callistemon citrinus, Cymbopogon citratus and Ocimum gratissimum) was evaluated in vitro against Acremonium apii and Colletotrichum dematium, respectively the causal agents of brown spots and anthracnose diseases of celery (Apium graveolens L.). Inhibition of fungi mycelial growth by essential oils, ethanol and aqueous extracts was assessed by using the supplemented media technique. Essential oils exhibited comparable activities against both fungi with minimum inhibitory concentration between 400 and 6000 ppm. Essential oil from O. gratissimum showed the highest inhibitory activity against both pathogens (400 ppm) followed by C. citratus (700 ppm and 800 ppm against A. apii and C. dematium, respectively), and then C. citrinus (6000 ppm). Ethanol extracts exhibited after the essential oils, the higher inhibitory activity against the two pathogens. Extract of C. citrinus was the most active with reductions of radial growth of 77.68% and 97.16% respectively against A. apii and C. dematium at 10000 ppm. Aqueous extracts at the same concentrations of ethanol extracts had little or no activity against both fungi. The fungitoxic potential of essential oils was higher than the one of the synthetic fungicide used as positive control. Our results suggest a promising potential of essential oils and ethanol extracts for botanicals control of celery fungal pathogens

Genetic divergence in common bean genotypes from the IRAD gene bank: morpho-agronomic characteristics, fungal and bacterial disease resistance, and opportunities for genetic improvement

For successful plant breeding in any crop species, the importance of diversity in the available germplasm population is known and established. Thirty-two common bean (Phaseolus vulgaris) genotypes from the IRAD gene bank in Cameroon were evaluated for divergence in terms of their morpho-agronomic traits, fungal disease resistance, and bacterial disease resistance to assess the opportunity for genetic improvement of the crop. The trait associations were estimated using correlation coefficients and genotypes were classified into groups using cluster and principal component analyses. Seven qualitative and 16 quantitative traits comprising growth, phenological, yield, and disease variables were evaluated in this study. The qualitative markers revealed the degree of polymorphism among the 32 common bean genotypes. The number of phenotypic classes per character (Na) ranged from 2 to 18, with an average of 5.14. The expected gene diversity (He) ranged from 0.37 to 0.93 (mean = 0.56). The number of effective phenotypic classes (Ne) ranged from 1.82 to 14.22, with a mean of 3.85. An extensive range of variation was evident for the majority of traits, highlighting their utility for characterizing common bean germplasm. Many qualitative traits, including seed coat color, seed shape, and seed size, and also some quantitative traits of economic importance including seed yield, were found to be highly variable within the collection, with the MAC55 genotype displaying the highest yield (32.65 g per plant). Four genotypes, namely MAC55, BOA-5-1M6, FEB 192, and Banguem showed resistance to the two main common bean diseases, angular leaf spot and common blight. We detected highly significant correlations among several traits related to yield. A high broad-sense heritability was found for most of the quantitative traits. We carried out two-dimensional principal component analysis and used hierarchical clustering to group the analyzed germplasm according to their phenotypic similitudes. The evidence of agro-morphological diversity in the present collection and the identification of discriminant characters between the available germplasm through the use of PCA analysis have significant implications for establishing breeding schemes in common bean

Morphological and molecular identification of pathogenic fungi of Monodora myristica Dunal kernels and their response to different phytoextracts

Identification of fungi from calabash nutmeg kernels was based on their morphological characteristics and analysis of the internal transcribed spacer (ITS) sequences of their genomic DNA. Antifungal activity of aqueous, methanolic and ethanolic extracts of four plants species (Azadirachta indica, Citrus sinensis, Moringa oleifera and Tithonia diversifolia) was tested in vitro at 50, 75, 100 and 125 mg/ml for aqueous extracts and 40, 60, 80 and 100 mg/ml for methanolic and ethanolic extracts. Mancozeb (1 mg/ml) and distilled water were used as positive and negative controls, respectively. The most frequently isolated fungi were Cercospora purpurea (34.28%), Fusarium oxysporum (23.81%) and Aspergillus flavus (17.14%). C. purpurea and F. oxysporum isolates were more aggressive after inoculation on healthy kernels. All the extracts tested, inhibited the growth of the fungi compared to the negative control, except the aqueous extract of T. diversifolia against C. purpurea and F. oxysporum and the methanolic extract of M. oleifera against F. oxysporum at 75 mg/ml. The efficiency of aqueous extracts of M. oleifera and C. sinensis was significantly lower (P<0.05) as compared to the reference fungicide on growth of A. niger at 125 mg/ml. Antifungal activity of methanolic extracts of A. indica, C. sinensis and T. diversifolia as well as ethanolic extracts of A. indica and M. oleifera was significantly equal to mancozeb at 100 mg/ml on A. flavus. Aqueous extracts of M. oleifera and methanolic extracts of A. indica and C. sinensis could be used for protection of Monodora myristica kernels against post-harvest fungi

Morphological and molecular identification of pathogenic fungi of Monodora myristica Dunal kernels and their response to different phytoextracts

Identification of fungi from calabash nutmeg kernels was based on their morphological characteristics and analysis of the internal transcribed spacer (ITS) sequences of their genomic DNA. Antifungal activity of aqueous, methanolic and ethanolic extracts of four plants species (Azadirachta indica, Citrus sinensis, Moringa oleifera and Tithonia diversifolia) was tested in vitro at 50, 75, 100 and 125 mg/ml for aqueous extracts and 40, 60, 80 and 100 mg/ml for methanolic and ethanolic extracts. Mancozeb (1 mg/ml) and distilled water were used as positive and negative controls, respectively. The most frequently isolated fungi were Cercospora purpurea (34.28%), Fusarium oxysporum (23.81%) and Aspergillus flavus (17.14%). C. purpurea and F. oxysporum isolates were more aggressive after inoculation on healthy kernels. All the extracts tested, inhibited the growth of the fungi compared to the negative control, except the aqueous extract of T. diversifolia against C. purpurea and F. oxysporum and the methanolic extract of M. oleifera against F. oxysporum at 75 mg/ml. The efficiency of aqueous extracts of M. oleifera and C. sinensis was significantly lower (P<0.05) as compared to the reference fungicide on growth of A. niger at 125 mg/ml. Antifungal activity of methanolic extracts of A. indica, C. sinensis and T. diversifolia as well as ethanolic extracts of A. indica and M. oleifera was significantly equal to mancozeb at 100 mg/ml on A. flavus. Aqueous extracts of M. oleifera and methanolic extracts of A. indica and C. sinensis could be used for protection of Monodora myristica kernels against post-harvest fungi

Conservation agriculture affects grain and nutrient yields of Maize (Zea Mays L.) and can impact food and nutrition security in Sub-Saharan Africa

Maize is a major staple and plays an essential role in food and nutrition security in Sub-Saharan Africa (SSA). Conservation agriculture (CA), a climate-smart agriculture practise based on minimum soil disturbance, crop residue retention, and crop diversification, has been widely advocated but without extensive research on the impact it may have on maize nutrient composition, and food and nutrition security. This study assessed the grain yield, macro- and micronutrient mineral content, and nutrient yield of eight maize varieties grown in Malawi, and how these are affected by CA practises over two seasons. The minerals were analysed by inductively coupled plasma (ICP) coupled to optical emission spectroscopy (OES) and to mass spectroscopy (MS). Grain yield and Se content differed among the varieties, while C, N, Fe, K, Mg, Mn, P, and Zn were similar. The local variety Kanjerenjere showed lowest grain and nutrient yields. The open-pollinated varieties (OPVs) concentrated more minerals than the F1 hybrids, but the latter showed higher yields for both grain and nutrients. Typical consumption of the eight maize varieties could fully meet the protein and Mg dietary reference intake (DRIs) of Malawian children (1–3 years), as well as Mg and Mn needs of adult women (19–50 years), but their contribution to dietary requirements was low for Fe (39–41%) and K (13–21%). The trials showed that CA increased grain yield (1.2- to 1.8-fold) and Se content (1.1- to 1.7-fold), but that it had no effect on C, K, Mg, P, and Zn, and that N (1.1- to 1.2-fold), Mn (1.1- to 1.8-fold), and Fe (1.3- to 3.4-fold) were reduced. The high increase in grain yield under CA treatments resulted in increased yields of protein and Se, no effect on the yields of K, Mg, Mn, P, Zn, and reduced Fe yield. Conservation agriculture could contribute in reducing the risk of Se deficiency in Malawian women and children but exacerbates the risk of Fe deficiency. A combination of strategies will be needed to mitigate some of the foreseen effects of climate change on agriculture, and food and nutrition security, and improve nutrient intake