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Organic amendments have been known to improve soil physical and chemical properties in sub-Saharan Africa. However, research information on how organic amendments affect aggregate stability and the degree of their effects in comparison to others is inadequate in Zambia. The study was carried out to assess the effect of organic amendments on soil dry aggregate stability and organic matter on soils from Chipata, Zambia. The specific objectives were to: Assess the effect of organic amendments on soil dry aggregate stability and assess if there is a relationship between soil organic matter and soil aggregate stability on a loamy ferric luvisol soil. Soil aggregates were collected from the top 10 cm of 10 m × 10 m plots in each treatment replicated five times. These aggregates were sieved through a 9.5 mm, and the retained aggregates on an 8 mm sieve were collected and used for aggregate stability analysis. Analysis of variance (ANOVA) of results showed significant differences among the means of five treatments: Sunn hemp, Tephrosia vogelii alley cropping, pigeon pea alley cropping, animal manure, and conventional treatments on a loamy ferric luvisol. Amending soils with Sunn hemp showed a significantly higher mean weight diameter (MWDd) of 2.393 compared to amending soils with T. vogelii alley cropping MWDd 1.767 (P value

Soil organic resource management practices such as use of green manure, cover crops, improved fallows, mulch, animal manure, compost and residue retention are options that promote the environment and potentially increase farmer crop yields and income. However, there have been low levels of adoption of most of these practices, and their ability to improve crop yields and farmer income has come into question. The objective of this study was to estimate the effects of the aforementioned practices on maize yields and income in Chipata district of Zambia. Using Matching algorithm strategies on data from 303 households, the study observed that only cover crops and improved fallows, significantly increased maize productivity by 16 - 21 and 22 - 31%, respectively. Only green manure and improved fallows increased household income by 26 - 28 and 48 - 67%, respectively. Since green manure did not show any significant influence on the production of maize, this later result could imply that the practice is expressing its significant effect on household income through cash crops such as cotton, soybean, tobacco and vegetables, which are common in the study area. The non-significance in the contribution of most of the practices to private benefits could be affecting the rates at which the practices are adopted. Since the significant contribution of the practices towards environmental sustainability is not debatable, there is need for payment of some mark-up to the adopters of the practices which could go towards compensation for production of environmental services through the practices. This will increase the private benefits accrued from adopting the practices, with the spill-over effects of increasing adoptability potential of the practices. Key words: Maize yields, income, organic resource management, matching strategies, Zambia.

For studying the effect of soil fertility management practices on N mineralization, urease activity and maize yield, replicated field trials were established in 2015 at Misamfu and Msekera agricultural research stations (ARS) representing two geo-climatic regions of Zambia. The soil at Msekera ARS is a sandy clay loam (SCL) from a Paleustult, while that at Misamfu is a loamy sand (LS) from a Kandiustult. The field trials had three categories of treatments namely legumes, traditional and conventional. The legumes group consisted of researcher-recommended legume-cereal intercrop systems of maize with Cajanus cajan, Crotalaria juncea and Tephrosia vogelii in combination with compound D (10% N, 20% P2O5, 10% K2O) and urea (46% N) at the recommended rate (200 kg ha-1) and half of the recommended rate (100 kg ha-1). Composted cattle manure and Fundikila, a special plant biomass management technique, were the inputs under the traditional category. The conventional category consisted of a treatment to which only chemical fertilizer was applied. Urease activity was determined in surface soil samples (0-20 cm) collected from the field trials after 3 years. For N mineralization, a laboratory incubation study was conducted over 13 weeks. For the laboratory incubation, an additional treatment to which no input was applied was included as control. Application of organic inputs significantly increased the potentially mineralizable N (No) by 127% to 256% on the LS and by 51% to 131% on the SCL in comparison to the control. Similarly, the cumulative N mineralized (Ncum) was twice or thrice higher where organic inputs had been applied in comparison to the control. The No followed the order traditional > legumes > conventional > control, while the mineralization rate constant (k) followed the order legumes > conventional > traditional > control on both soils. The rate of N mineralization was significantly higher on the LS than the SCL. Higher rates of chemical fertilizer resulted in high Ncum and higher maize yield. Maize yield was significantly and positively correlated to Ncum, but inversely correlated to the amount of applied N that was mineralized (%Nmin). Urease activity was stimulated by application of organic inputs and suppressed by higher rates of chemical fertilizers. The type of organic inputs; the rate of chemical fertilizers; and soil texture are factors influencing N mineralization and maize yield. Urease activity was largely influenced by the rate of chemical fertilizer, but not the type of organic inputs or soil texture.

A field experiment was undertaken on farmers’ fields adjacent to a large mine tailings dam in the Zambian mining town of Kitwe. Experimental plots were located close to the tailings (≤ 200 m) or further away (300–400 m) within the demarcated land farmed by the same community. This study evaluated the uptake of Cd, Cu, Ni, Pb and Zn by pumpkin leaves and maize grown in soil amended with lime and manure applied at agronomic rates, and the subsequent risk of dietary exposure to the local community, typical of many similar situations across the Zambian Copperbelt. Treatments, combinations of lime and manure (present or absent), were applied to subplots selected independently and randomly within each main plot, which represented variable geochemistry across this study site as a result of windblown/rain-driven dust from the tailings. Total elemental concentrations in crops were determined by ICP-MS following microwave-assisted acid digestion. Concentrations of Cu and Pb in pumpkin leaves were above the prescribed FAO/WHO safe limits by 60–205% and by 33–133%, respectively, while all five metals were below the limit for maize grain. Concentration of metals in maize grain was not affected by the amendments. However, lime at typical agronomic application rates significantly reduced concentrations of Cd, Cu, Pb and Zn in the pumpkin leaves by 40%, 33%, 19% and 10%, respectively, and for manure Cd reduced by 16%, while Zn increased by 35%. The uptake of metals by crops in locations further from the tailings was greater than closer to the tailings because of greater retention of metals in the soil at higher soil pH closer to the tailings. Crops in season 2 had greater concentrations of Cu, Ni, Pb and Zn than in season 1 due to diminished lime applied only in season 1, in line with common applications on a biannual basis. Maize as the staple crop is safe to grow in this area while pumpkin leaves as a readily available commonly consumed leafy vegetable may present a hazard due to accumulation of Cu and Pb above recommended safe limits.

SI; International audience; Boosting the productivity of smallholder farming systems continues to be a major need in Africa. Challenges relating to how to improve irrigation are multi‐factor and multisectoral, and they involve a broad range of actors who must interact to reach decisions collectively. We provide a systematic reflection on findings from the research project EAU4Food, which adopted a transdisciplinary approach to irrigation for food security research in five case studies in Ethiopia, Mali, Mozambique, South Africa and Tunisia. The EAU4Food experiences emphasize that actual innovation at irrigated smallholder farm level remains limited without sufficient improvement of the enabling environment and taking note of the wider political economy environment. Most project partners felt at the end of the project that the transdisciplinary approach has indeed enriched the research process by providing different and multiple insights from actors outside the academic field. Local capacity to facilitate transdisciplinary research and engagement with practitioners was developed and could support the continuation and scaling up of the approach. Future projects may benefit from a longer time frame to allow for deeper exchange of lessons learned among different stakeholders and a dedicated effort to analyse possible improvements of the enabling environment from the beginning of the research process. © 2020 The Authors. Irrigation and Drainage published by John Wiley & Sons Ltd on behalf of International Commission for Irrigation and Drainage

Expanding arable land under irrigation is cardinal in the quest to attain Africa's aspiration of transforming agriculture and realizing its true value and positive impact on wealth creation, economic growth, food security and nutrition for all. Over the last three to four decades, many initiatives have been designed to harness both small- and large-scale irrigation technologies towards increasing agricultural production and productivity. The EAU4Food (European Union and African Union cooperative research to increase food production in irrigated farming systems in Africa) project was a collaborative project under the EU–African Union Scientific Partnership aimed at enabling the successful adoption and upscaling of appropriate irrigation support innovations. The project applied a transdisciplinary approach to design, test and disseminate innovations across the continent. The project was designed to gain better insights vis-à-vis how the innovation process can be enhanced, and to share insights for supporting the implementation of national agricultural development programmes and strategies conceived within the context of the Comprehensive Africa Agriculture Development Programme (CAADP) framework. This note highlights linkages between the CAADP framework and the EAU4Food project and suggests some future areas of attention on Africa's agenda for enhanced agricultural production, facilitated under the auspices of CAADP.

Cassava is a staple food and a major source of income for many smallholder farmers. However, its yields are less than 6 t ha-1 compared to a potential yield of 20-25 t ha-1 in Zambia. Understanding cropping practices and constraints in cassava production systems is imperative for sustainable intensification. Therefore, a survey of 40 households each with three fields of cassava at 12, 24, and 36 months after planting (MAP) was conducted. Analyzed soil data, leaf area index (LAI), intercepted photosynthetically active radiation, and management practices from 120 fields were collected and subjected to descriptive statistics. To explain yield differences within the same cassava growth stage group, the data were grouped into low- and high-yield categories using the median, before applying a nonparametric test for one independent sample. Stepwise regressions were performed on each growth stage and the whole dataset to determine factors affecting tuber yield. Cassava intercropping and monocropping systems were the main cropping systems for the 12 and 24-36 MAP, respectively. Cassava yields declined by 209 and 633 kg ha-1 at 12 and 36 MAP due to soil nutrient depletion for each year of cultivation until field abandonment at 8-9 years. Fresh cassava yields ranged from 3.51-8.51, 13.52-25.84, and 16.92-30.98 t ha-1 at 12, 24, and 36 MAP, respectively. For every one unit increment in exchangeable K (cmol (+)/kg soil), cassava yield increased by 435, 268, and 406 kg ha-1 at 12, 24, and 36 MAP, respectively. One unit increment of magnesium (cmol (+)/kg soil) gave the highest yield increase of 525 kg ha-1 at 24 MAP. The low levels of soil organic carbon explained the deficient nitrogen in cassava fields, which limits the LAI growth and consequently reduced intercepted radiation and low yields. The effect of exchangeable K on growth was limited by the moderate availability of Mg and low N, thus the need for balanced fertilizer regimes. © 2021 Peter Kaluba et al.

This study presents an analysis of the effects of manure and lime commonly used to improve agricultural productivity and evaluates the potential for such soil amendments to mobilise/immobilise metal fractions in soils contaminated from nearby mine tailings in the Zambian Copperbelt. Lime and manure were applied at the onset of the study, and their effects were studied over two planting seasons, i.e. 2016-17 and 2017–18. Operationally defined plant-available Cd, Cu, Ni, Pb and Zn in the soil, were determined by extraction with DTPA-TEA (diethylenetriaminepentaacetic acid-triethanolamine) and 0.01 M Ca(NO3)2, before, and after, applying the amendments. In unamended soils, Cd was the most available and Ni the least. Lime application decreased extractable Cd, Cu, Ni, Pb and Zn. The response to lime was greater in soils with an initially acidic pH than in those with approximately neutral pH values. Manure increased DTPA extractable Zn, but decreased DTPA and Ca(NO3)2 extractable Cd, Cu and Pb. Combined lime and manure amendment exhibited a greater reduction in DTPA extractable Cd, Ni, Pb, Zn, as well as for Ca(NO3)2 extractable Cd compared to separate applications of lime and manure. The amendments had a significant residual effect on most of the soil fractions between season 1 and 2. The results obtained in this study showed that soil amendment with minimal lime and manure whilst benefiting agricultural productivity, may significantly reduce the mobility or plant availability of metals from contaminated agricultural soils. This is important in contaminated, typical tropical soils used for crop production by resource poor communities affected by mining or other industrial activities., Copperbelt; Lime; Manure; Mine tailings; Bioavailable metals; Agricultural soil science; Environmental analysis; Environmental assessment; Environmental chemistry; Environmental geochemistry; Environmental hazard; Environmental health; Environmental management; Soil science.

Health risks due to heavy metal (HM) contamination is of global concern. Despite concerns of high levels of HMs in soils near Kabwe mine in Zambia, edible crop production is common, posing potential health risks. This study assessed the potential of chicken manure (CM), triple superphosphate (TSP) and a blended fertilizer (BF, consisting of Nitrogen, Phosphorous and Potassium (NPK) fertilizer and composted chicken manure) to reduce lead (Pb), zinc (Zn) and cadmium (Cd) in soils and their accumulation in maize grown near the Kabwe mine. Maize was grown to maturity and its HM concentrations and associated health risk indices were calculated. All soil amendments decreased bioavailable soil Pb concentrations by 29&ndash, 36%, but only CM decreased Zn, while the amendments increased or had no effect on Cd concentrations compared to the control. The amendments reduced Pb (&gt, 25%) and Zn concentrations (&gt, 18%) in the maize stover and grain. However, Cd concentrations in maize grain increased in the BF and TSP treatments. Bioaccumulation factors showed that Cd had the highest mobility from the soil into maize stover and grain, indicating the need for greater attention on Cd in Kabwe despite its apparently lower soil concentration compared to Pb and Zn. The hazard quotients for Pb and Cd were much greater than one, indicating a high risk of possible exposure to toxic levels by people consuming maize grain grown in this area. This study demonstrated the significant potential of manure and phosphate-based amendments to reduce Pb and Zn, and to some extent Cd, uptake in maize grain and consequently reduce associated health risks.

A field experiment was undertaken on farmers' fields adjacent to a large mine tailings dam in the Zambian mining town of Kitwe. Experimental plots were located close to the tailings (≤ 200 m) or further away (300-400 m) within the demarcated land farmed by the same community. This study evaluated the uptake of Cd, Cu, Ni, Pb and Zn by pumpkin leaves and maize grown in soil amended with lime and manure applied at agronomic rates, and the subsequent risk of dietary exposure to the local community, typical of many similar situations across the Zambian Copperbelt. Treatments, combinations of lime and manure (present or absent), were applied to subplots selected independently and randomly within each main plot, which represented variable geochemistry across this study site as a result of windblown/rain-driven dust from the tailings. Total elemental concentrations in crops were determined by ICP-MS following microwave-assisted acid digestion. Concentrations of Cu and Pb in pumpkin leaves were above the prescribed FAO/WHO safe limits by 60-205% and by 33-133%, respectively, while all five metals were below the limit for maize grain. Concentration of metals in maize grain was not affected by the amendments. However, lime at typical agronomic application rates significantly reduced concentrations of Cd, Cu, Pb and Zn in the pumpkin leaves by 40%, 33%, 19% and 10%, respectively, and for manure Cd reduced by 16%, while Zn increased by 35%. The uptake of metals by crops in locations further from the tailings was greater than closer to the tailings because of greater retention of metals in the soil at higher soil pH closer to the tailings. Crops in season 2 had greater concentrations of Cu, Ni, Pb and Zn than in season 1 due to diminished lime applied only in season 1, in line with common applications on a biannual basis. Maize as the staple crop is safe to grow in this area while pumpkin leaves as a readily available commonly consumed leafy vegetable may present a hazard due to accumulation of Cu and Pb above recommended safe limits.

Rice is one of the staple food crops and is a profitable smallholder cash crop in Zambia. It has the potential to contribute significantly to increased incomes and employment among rural producers. However, rice is the only staple crop in the country for which domestic production does not meet or exceed domestic demand. Low productivity is one of the factors that contribute to this. One necessary step towards addressing this problem is the identification of land with greatest potential for rice production, as well as the identification of land-based limitations which might be overcome by improved management. The aim of this study was to develop a land suitability index for rainfed paddy rice production reflecting expert opinion and published studies based on climatic, topographic and soil properties. Land suitability was evaluated using a method which accounts for important multiple factors, and which considers their joint effect in terms of a hierarchical model of constraints. The suitability classes were ranked according to the FAO land suitability classification as: Highly Suitable (S1), Moderately Suitable (S2), Marginally Suitable (S3), Currently Not Suitable (N2), and Permanently Not Suitable (N1). Results showed that there is limited potential for rainfed paddy rice production in Zambia with

Digital soil maps describe the spatial variation of soil and provide important information on spatial variation of soil properties which provides policy makers with a synoptic view of the state of the soil. This paper presents a study to tackle the task of how to map the spatial variation of soil pH across Zambia. This was part of a project to assess suitability for rice production across the country. Legacy data on the target variable were available along with additional exhaustive environmental covariates as potential predictor variables. We had the option of undertaking spatial prediction by geostatistical or machine learning methods. We set out to compare the approaches from the selection of predictor variables through to model validation, and to test the predictors on a set of validation observations. We also addressed the problem of how to robustly validate models from legacy data when these have, as is often the case, a strongly clustered spatial distribution. The validation statistics results showed that the empirical best linear unbiased predictor (EBLUP) with the only fixed effect a constant mean (ordinary kriging) performed better than the other methods. Random forests had the largest model-based estimates of the expected squared errors. We also noticed that the random forest algorithm was prone to select as “important” spatially correlated random variables which we had simulated.

There are challenges that limit the use of organic inputs for soil fertility management. Amongst them is the limited knowledge of factors that affect rates of decomposition and nutrient release from different organic inputs. A study was conducted on surface soil samples of two Ultisols to determine factors affecting carbon (C) mineralization from selected organic inputs. A loamy sand (LS) from a Kandiustult and a sandy clay loam (SCL) from a Paleustult were used. Fine earth fractions of the soils mixed with organic inputs with and without chemical fertilizer were incubated for 13 weeks and the CO2 evolved was measured. Organic inputs used were biomasses of Cajanus cajan, Tephrosia vogelii, Crotalaria juncea, Mucuna pruriens, a mixture of native grasses and shrubs and composted cattle manure. The latter two inputs are traditionally used by farmers, while the leguminous plants were recommended by scientists. Treatments with chemical fertilizer only, representing the conventional farming practice, and a control with soil alone were included. Addition of organic inputs with or without fertilizer increased total CO2 emissions by 81 to 129% on the LS and by 18 to 34% on the SCL. Adding chemical fertilizer significantly (p < 0.05) increased C mineralization rate constant (k) by 116% on the LS and 48% on the SCL. The mean residence time of organic carbon from treatments grouped by input type followed the order: Control > Traditional > Legumes > Conventional on both soils. In general, the k on the LS was double that on the SCL. The type of organic input, soil texture and application of chemical fertilizer significantly affected C mineralization rates from the soils.

Heavy metals are of environmental significance due to their effect on human health and the ecosystem. One of the major exposure pathways of Heavy metals for humans is through food crops. It is postulated in the literature that when crops are grown in soils which have excessive concentrations of heavy metals, they may absorb elevated levels of these elements thereby endangering consumers. However, due to land scarcity, especially in urban areas of Africa, potentially contaminated land around industrial dumps such as tailings is cultivated with food crops. The lack of regulation for land-usage on or near to mine tailings has not helped this situation. Moreover, most countries in tropical Africa have not defined guideline values for heavy metals in soils for various land uses, and even where such limits exist, they are based on total soil concentrations. However, the risk of uptake of heavy metals by crops or any soil organisms is determined by the bioavailable portion and not the total soil concentration. Therefore, defining bioavailable levels of heavy metals becomes very important in HM risk assessment, but methods used must be specific for particular soil types depending on the dominant sorption phases. Geochemical speciation modelling has proved to be a valuable tool in risk assessment of heavy metal-contaminated soils. Among the notable ones is WHAM (Windermere Humic Aqueous Model). But just like most other geochemical models, it was developed and adapted on temperate soils, and because major controlling variables in soils such as SOM, temperature, redox potential and mineralogy differ between temperate and tropical soils, its predictions on tropical soils may be poor. Validation and adaptation of such models for tropical soils are thus imperative before such they can be used. The latest versions (VI and VII) of WHAM are among the few that consider binding to all major binding phases. WHAM VI and VII are assemblages of three sub-models which describe binding to organic matter, (hydr)oxides of Fe, Al and Mn and clays. They predict free ion concentration, total dissolved ion concentration and organic and inorganic metal ion complexes, in soils, which are all important components for bioavailability and leaching to groundwater ways. Both WHAM VI and VII have been applied in a good number of soils studies with reported promising results. However, all these studies have been on temperate soils and have not been tried on any typical tropical soils. Nonetheless, since WHAM VII considers binding to all major binding phases, including those which are dominant in tropical soils, it would be a valuable tool in risk assessment of heavy metals in tropical soils. A discussion of the contamination of soils with heavy metals, their subsequent bioavailability to crops that are grown in these soils and the methods used to determine various bioavailable phases of heavy metals are presented in this review, with an emphasis on prospective modelling techniques for tropical soils.

Improved fallows with leguminous trees have been developed in Southern Africa as a viable alternative to inorganic fertilizers but the changes in soil properties that are responsible for crop productivity improvement and implications of mixing litter and fresh leaves from the same tree species on soil fertility are not fully understood. Our objectives were to quantify (1) some changes in soil properties that are responsible for crop production improvement under improved fallow systems; (2) the N mineralization patterns of mixtures of litter and fresh leaves from the same tree species. The treatments used in the study were 2-year planted Sesbania sesban (sesbania) and Cajanus cajan (cajanus) and controls of natural fallow, continuous fertilized and unfertilized maize. At fallow clearing sesbania contributed 56 kg N ha−1 through litter and fresh leaves. Sesbania (fresh leaves + litter) showed high N mineralization after 10 weeks compared to the mixture of cajanus fresh leaves with litter. Maize yields were significantly correlated with preseason NO3−-N and total inorganic-N content of the top 20-cm soil layer. Soil penetrometer resistance at 4 weeks after planting was lowest in the sesbania land-use system (2.2 Mpa), whereas the highest percentage of water-stable aggregates at fallow clearing and crop harvest was in sesbania (83%) and cajanus (77%), respectively. The improved soil conditions and N contribution of sesbania and cajanus fallows to the subsequent maize crop was evidenced by increased maize yields of between 170–200% over maize without fertilizer.

A study where Chinese cabbage and pumpkin crops were grown on sandy loam and clay loam soils and irrigated with water contaminated with five levels of contamination from 0 (control), 25, 50, 75 and 100% of smelter water was carried out in a greenhouse. Copper concentration in Chinese cabbage ranged from 4.0 mg/kg in control treatments to 539.0 mg/kg in 100% contaminated water. In pumpkin, Cu ranged from 9.0 mg/kg in control to 142.0 mg/kg when irrigate with 100% contaminated water. Mean Cu in plants grown on sandy loam soil was 217.4 mg/kg dry and 79.3 mg/kg when grown on clay loam. Co in plants grown on sandy loam soil was 86.6 mg/kg and 47.0 mg/kg on clay loam soil. Increasing above ground tissue Cu in Chinese cabbage results in biomass yield decrease according to the equation Y = 7.624e-0.0016x, (R2 = 0.74) and in pumpkin decreased according to the equation Y = 8.4895e-0.004x (R2 = 0.58).This study suggests that Chinese cabbage tends to accumulate higher amounts of Cu and Co than pumpkin. It can be concluded from this study that irrigating crops with contaminated results in higher uptake of contaminants and reduced biomass on sandy loam than clay loam soils.

With declining fertility levels of soils and the high cost of agricultural inputs, such as commercial fertilizers and pesticides, the use of organic inputs has increased in Zambia. While neem products have been shown to improve soil fertility status, several negative effects on soil organisms have also been cited. The negative effects have been attributed to several secondary metabolites produced by the neem plant. In Zambia, neem leaf extract is applied by small scale farmers to enhance soil fertility and promote crop productivity. This study reports the suitability of aqueous neem leaf extract as a soil amendment and its effect on soil microbial biomass and activity in local soils. Neem leaves were characterized before being used to prepare aqueous neem extract in the concentrations 2, 5, 10, 15, and 20 % in water. The extract was characterized for selected mineral components and then applied to 5 kg of soil on a weekly basis for five weeks. Each week, for ten weeks, the effect of the extract on microbial biomass and activity were determined using the Chloroform Fumigation and Incubation (CFI) and soil respiration methods, respectively. Selected soil chemical characteristics were determined at the start and end of the experiment. Results indicated that the chemical composition of the neem leaves was comparable to that observed by others and was similar to that of other tree leaves used for preparing leaf extracts. Amending soils with neem did not significantly improve selected chemical properties but only marginally increased soil calcium levels. Neem leaf extract enhanced soil microbial activity up to 10 %, but showed inhibitory effects at 15 and 20 % concentrations. Microbial biomass was also depressed by neem leaf extract at 20 %. The reduction in both microbial activity and biomass was possibly due to the negative effects of the neem secondary metabolites in the leaf extract at these higher concentrations. Although the application of neem leaf extract at 10 % percent or higher can inhibit both microbial biomass and activity, some mineralizable components in the extracts can support growth and activity of some microorganisms in the soil. Based on these results, the application of neem leaf extract at 10 % percent or higher can inhibit both microbial biomass and activity and marginally improve soil Ca levels. The use of neem leaf extract can therefore be of benefit to soils with critically low levels of Ca.

What the world is experiencing is clearly pointing to undesirable climatic changes with potential catastrophic consequences. This is evident from rising environmental temperatures associated 12-4with longer and deeper droughts, declining water resourcesin spite of increased overall rate of groundwater recharge in cold 56-7climates, predictable declining crop yieldsand complex 7-9variable crop responses. These changes are due to a complex phenomenon with diverse and widespread effects; global climate change.