**2. Agriculture in the Middle East and North Africa**

Soil types, crops and trade patterns vary considerably across the Middle East and North Africa (MENA) region [23], but all countries are affected by water scarcity. The region comprises arid, semi-arid and hyper-arid areas, but even comparatively water-rich countries are affected by severe water stress [24], caused in part by economic incentives to cultivate water-intensive crops. Crop choice therefore plays an important role [25]. The water crisis is aggravated by deterioration of water quality caused by pesticides and nutrient runoff [26, 27], while groundwater is impacted by leaching and excessive pumping [28, 29]. Rural flight and decline of rural populations in several countries, such as Iran and Turkey [30] can reflect reduced need for labour due to mechanisation but may also reflect insecure livelihoods and difficult conditions of farmers [31, 32], while rural populations are also affected by displacement caused by disasters related to extreme weather, including forest fires, flooding and crop failure. The region is heavily dependent on imports of cereals. Both price fluctuations and transitions away from hydrocarbons globally will lead to decline in hydrocarbons exports on which many states of the region depend, affecting their ability to ensure food security through imports [23]. However, vested interests in exploiting hydrocarbons for the production of petrochemicals for agricultural use, as well as the existence of major phosphate deposits are likely to influence national economic diversification policies.

Large parts of the Middle East and North Africa are affected by protracted conflicts, internally displaced populations, and high volatility [33, 34]. Political and economic crises are affecting access to food, clean water and energy for large population groups [35], while agriculture is impacted by rising costs of fertilizers, pesticides, fuel and machinery, combined with disruptions to infrastructure and processing, storage and distribution systems for agricultural produce. These challenges will increasingly be aggravated by climate change [36–41] and environmental degradation. Consequently, resilient food systems and food security will become issues of major concern for the region [42, 43], highlighting the question of climate adaptation strategies for farmers [31, 44–46].

Research on organic fertilizers in the MENA region from an environmental perspective is as yet relatively limited. Thus, a Scopus search on October 14, 2021, with the search term 'organic fertilizers' yielded 517 articles and reviews in English concerning agricultural sciences in the MENA region for the period 2017–2021, compared to 6558 worldwide for the same period. Publications in this field were dominated by Iran, Iraq, Egypt and Turkey (92%). Only 102 (20%) of the 517 MENA publications related to environmental or earth and planetary sciences. Within these 102, a mere 5 directly dealt with water-related issues, (including keywords such as irrigation, water quality, water stress, arid regions or groundwater), and none of the overall 517 publications on organic fertilizers mentioned climate adaptation or mitigation. In view of the interrelated urgent challenges that climate change and food security pose for the region, I will therefore draw on the international literature, to situate the use of organic fertilizers with respect to these challenges.

#### **3. Environmental impacts of agriculture**

Climate and environmental impacts of fertilizer use and soil management practices include not only emissions and pollution from production of fertilizer [47], but also those linked to the mechanised and chemical-intensive agricultural production systems they are associated with, impacts of nutrient runoff and chemicals [48, 49] on receiving water bodies, as well as impacts connected to food processing, storage, transport and waste. Effects on the world's oceans are concerning. Unsustainable land use poses a threat for climate and biodiversity [20, 36, 50]. Agricultural land use and soil management practices are from a climate and environmental perspective of relevance for carbon storage [51], but also with respect to nutrient runoff, and persistent chemicals, and to emissions of N2O and CH4 [52]. According to the IPCC, the use of fertilizers has increased nine-fold since 1961 [53], and soil management accounts for half of greenhouse gas (GHG) emissions of the agricultural sector [54].

#### **3.1 IPCC estimates of climate impacts and mitigation potentials**

No global data are available specifically for agricultural CO2 emissions, and there is considerable uncertainty concerning net balance of CO2 land-atmosphere exchanges. However, land is an overall carbon sink, with a net land-atmosphere flux from response of vegetation and soils of −6 ± 3.7 GtCo2yr (averages for 2007–2016). The capacity of land to act as a carbon sink is expected to decrease as an effect of global warming. The major impacts of agricultural land use (food, fibre and biomass production) on CO2 (5.2 ± 2.6 GtCo2yr) are connected to deforestation, drainage of soils and biomass burning rather than to the net flux balance directly caused by different fertilization practices. Numbers regarding CO2 emissions from land use can be compared to net global anthropogenic CO2 emissions, which are estimated at 39.1 ± 3.2 GtCo2yr. In addition to land use impacts, agriculture causes CO2 emissions in the order of 2.6–5.2 GtCo2yr through activities in the global food system, including grain drying, international trade, synthesis of inorganic fertilizers, heating in greenhouses, manufacturing of farm inputs, and agri-food processing [55].

Agricultural land use directly represents 40% (4.0 ± 1.2 GtCo2eq yr) of total net global anthropogenic CH4 emissions, and represents 79% (2.2 ± 0.7 GtCo2eq yr) of total net global N2O emissions. CH4 emissions are mainly caused by ruminants and rice cultivation. Half of N2O emissions are caused by livestock, and the rest mainly by N fertilization (including inefficiencies). Total average net global GHG emissions (CO2, CH4 and N2O) for all sectors 2007-2016 are estimated at 52.0 ± 4.5 GtCo2eq yr, of which agriculture directly contributes with 17-22% (not including impacts of agriculture on land available for forests), or 21-37% (including agricultural land expansion and other contributions of the food system) [55]. Importantly, agricultural soil carbon stock change is not included in these statistics. Irrigation and agricultural land management contribute to making forests vulnerable to fires, while desertification [37] amplifies global warming through release of CO2, but such emissions as well as impacts from runoff on net fluxes from wetlands, water bodies and oceans are not included in the above figures.

Although net GHG emissions are often converted to CO2 equivalents for accounting purposes, different gases remain in the atmosphere for different periods of time and will consequently have different impacts on the progression of global warming. The specific proportions of GHG will affect the likelihood of crossing critical thresholds and tipping points, setting off cascades (cf. Lenton et al. [56]) with ecosystem collapse and mass extinctions, while driving biophysical processes that further aggravate the dynamics. Effects of mitigation measures also have varying timelines.

The creation of reactive N in agriculture has significant environmental impacts [57], and excessive application of nitrogen can increase nitrous oxide emissions without improving crop yields [54]. On average, only 50% of N is used, but in countries with heavy N fertilization the efficiency can be much lower, and the potential for mitigation therefore increases [7, 36]. Use of fertilizer is responsible for more than 80% of N2O emissions increase since the preindustrial era [58]. Ruminant

livestock is the overall main source of CH4 from agricultural practices [55, 59], and among organic fertilizers cattle manure has therefore been widely studied. Rice cultivation makes the greatest contribution to CH4 emissions from agricultural soils [60]. Both water logging and soil compaction also contribute to CH4 emissions [61].
