Nitrogen management in irrigated cotton-based systems under conservation agriculture on salt-affected lands of Uzbekistan

Intensive soil tillage and mismanagement of irrigation water and fertilizers reduce soil organic matter and increase secondary soil salinization. These processes are increasing production costs, reducing soil fertility and threatening the sustainability of crop production systems in the irrigated drylands of Uzbekistan, Central Asia. These adverse effects can be counterbalanced by conservation agriculture (CA) practices combined with optimum nitrogen (N) management. This has been demonstrated in rainfed areas, but only sparse findings exist for irrigated crop production. Therefore, the effects of tillage, crop residue management and N rates were examined on growth, yield, water and N use efficiency (NUE), and the N balance of crops as well as the soil salinity dynamics in two cotton-based systems, (i) cotton/wheat/maize and (ii) cotton/cover-crop/cotton, in Khorezm, a region in northwest Uzbekistan. Also, on smaller subplots the effect of three different furrow irrigation techniques on the distribution and management of soil salinity on raised beds was studied. These techniques were every-furrow (EFI), alternating skip furrow (ASFI), and permanent skip furrow irrigation (PSFI). The split-plot experiments with four replications were conducted from 2008-2009 in an area covering 3 ha. They included two tillage methods (permanent raised bed, BP; and conventional tillage, CT); two residue levels (retaining the maximum possible amount, RR; and removing residues according to farmers’ practices, RH); and three N levels: no application (N- 0); low-N (125 kg N ha-1 for cotton and 100 kg N ha-1 for wheat and maize); and high-N (250 kg N ha-1 for cotton, and 200 kg N ha-1 for wheat and maize). These treatments were evaluated on land previously cropped using conventional means (CT). The official N recommendation for the study region is 160-180, 180 and 150 kg N ha-1 for cotton, wheat and maize, respectively. Raw cotton yield and its components were not affected by tillage methods in both cotton-based rotation systems in the first season after transformation from CT to CA practices. However, already one cropping cycle later, wheat and maize under BP produced, respectively, 12 and 42% higher grain yields than under CT. Under BP, water productivity increased in wheat by 27% and in maize by 84%, whilst 12% less water was applied during wheat and 23% during maize production compared to CT. Nitrogen applications significantly increased the growth and yield of all crops under both tillage practices. However, the response to N applied was higher under BP than CT. Increased boll density and boll weight in cotton, number of spikes m-2 and grains per spike in wheat, and cob density and number of grains per cob in maize predominantly caused higher yields. Total NUE in BP was higher by 42% in cotton, 12% in wheat, and 82% in maize crops compared to CT. With high N applications, the apparent positive N balance (N loss) in BP was lower by 71% in the cotton/wheat/maize system and by 53% in the cotton/cover-crop/cotton system than under CT. Residue retention in BP increased grain yield of wheat and maize in the absence of N applications, but had an insignificant effect on crop yield at low-N and high-N application rates. Residue retention had no effect at all N levels under CT. In BP, it minimized the rate of soil salinity increase by 45% in the top 10 cm and by 18% in the top 90 cm soil profile compared to RH. The inclusion of a winter cover crop in the cotton-cotton rotation reduced the groundwater nitrate contamination considerably, and increased the NUE under both BP and CT. Soil salinity on top of the beds increased significantly with EFI and ASFI compared to PSFI. The latter practice of salinity management provided the less saline area towards the irrigated furrow, as salts accumulated on the dry furrows. These accumulated salts can be leached, which reduced the salinity level in the center of the beds two-fold compared to EFI and ASFI. For cotton, wheat and maize, grown in rotation, BP and residue retention with application of the recommended N for maize and ~15% less than recommended N for cotton and wheat were in many aspects superior to CT practices. Permanent bed cotton cultivation with a winter cover crop is a suitable alternative for cotton-cotton based systems in irrigated drylands of Uzbekistan. Should residues not be available, PSFI is a suitable alternative for salt management in raised bed planting in salt-affected irrigated lands.Stickstoffmanagement im bewässerten Baumwollanbausystem mit konservierender Bodenbearbeitung (conservation agriculture) in versalzten Böden in Usbekistan Intensive Bodenbearbeitung und inadäquates Management von Bewässerungswasser und Düngemitteln reduzieren organisches Material im Boden und führen zu zunehmender sekundärer Bodenversalzung. Diese Prozesse steigern die Produktionskosten, schmälern die Bodenfruchtbarkeit und bedrohen damit letztendlich die Nachhaltigkeit der Anbausysteme in den bewässerten Trockengebieten von Usbekistan. Konservierende Bodenbearbeitung (CA), die mit optimalen Stickstoff-(N)- gaben kombiniert wird, kann den obengenannten negativen Auswirkungen entgegenwirken. Dies ist in Gebieten mit Regenfeldbau demonstriert worden, es gibt aber kaum Daten für den Bewässerungsanbau. Daher untersucht diese Studie die Auswirkungen von Bodenbearbeitung, Ernterückständen und Stickstoffgaben auf Pflanzenwachstum und -erträge sowie Wasserproduktivität, Effizienz von Stickstoffanwendungen (NUE), Stickstoffbilanz der Anbaupflanzen sowie Bodenversalzungsdynamik in zwei Baumwollsystemen: (i) Baumwolle/Weizen/Mais und (ii) Baumwolle/Gründüngung/Baumwolle in der Region Khorezm im Nordwesten Usbekistans. Außerdem wurden auf kleineren Versuchsparzellen die Auswirkungen von drei verschiedenen Furchenbewässerungsmethoden auf Verteilung und das Management von Bodenversalzung auf erhöhtem Pflanzbett (BP) untersucht und zwar Bewässerung jeder Furche (EFI), alternierendes Auslassen jeweils einer Furche (ASFI), und permanentes Auslassen der zweiten Furche (PSFI). Die split-plot Feldversuche wurden mit vier Wiederholungen 2008-2009 auf einer Fläche von 3 ha durchgeführt. Untersucht wurden zwei Bodenbearbeitungsmethoden (permanente Pflanzbetten, BP) und konventionelle Bodenbearbeitung, CT); zwei Mengen von Ernterückständen (Belassen der höchstmöglichen Menge, RR, und Entfernen der Rückstände wie durch die Bauern praktiziert, RH); und drei N-Mengen: keine N-Gabe (N-0), niedrige N-Gaben (125 kg N ha-1 für Baumwolle und 100 kg N ha-1 für Weizen und Mais); und hohe N-Gaben (250 kg N ha-1 für Baumwolle und 200 kg N ha-1 für Weizen und Mais). Die Versuche wurden auf Land durchgeführt, das zuvor konventionell bearbeitet wurde (CT). Offiziell werden für das Untersuchungsgebiet Gaben von 160-180, 180 bzw. 150 kg N ha-1 für Baumwolle, Weizen bzw. Mais empfohlen. Die Bodenbearbeitungsmethode hatte keinen Einfluss auf den Rohbaumwollertrag oder seine Bestandteile in beiden Baumwollrotationssystemen in der ersten Anbauperiode nach der Umwandlung von CT zu CA. Jedoch bereits einen Anbauzyklus nach der Einführung von CA lagen der Weizen- bzw. Maisertrag unter BP 12% bzw. 42% höher als unter CT. Verglichen mit CT nahm unter BP die Wasserproduktivität bei Weizen um 27% und bei Mais um 84% zu, während 12% weniger Wasser bei der Weizen- und 23% bei der Maisproduktion verbraucht wurde. Die Stickstoffgaben führten zu einer signifikanten Zunahme des Pflanzenwachstums und Ertrags aller Anbaupflanzen in beiden Bodenbearbeitungsmethoden, jedoch war der Effekt des Stickstoffs höher unter BP als unter CT. Die erhöhte Dichte und Gewicht der Baumwollbäusche und Anzahl der Weizenähren m-2 bzw. -körner pro Ähre bei Weizen, und die Kolbendichte und Anzahl der Körner pro Kolbe bei Mais führten zu höheren Erträgen. Bei BP war die Gesamt-NUE 42% höher bei Baumwolle, 12% bei Weizen und 82% bei Mais im Vergleich zu CT. Bei hohen Stickstoffgaben war die apparente positive N-Bilanz (N-Verlust) bei BP 71% niedriger im Baumwoll-/Weizen-/ Maissystem und 53% im System Baumwolle/Gründüngung /Baumwolle als bei CT. Das Belassen der Ernterückstände führte bei BP zu einem erhöhten Körnerertrag bei Weizen und Mais bei N-0, aber der Effekt war nichtsignifikant bei niedrigen bzw. hohen N-Mengen. Bei CT wurde bei keiner der N-Mengen eine Wirkung beobachtet. Bei BP führten die Rückstände zu einer um 45% bzw. 18% geringeren Zunahme der Bodenversalzung in den oberen 10 bzw. 90 cm des Bodens im Vergleich zu RH. Eine Winter-Gründüngung in der Baumwolle-Baumwolle-Rotation führte zu einer bedeutenden Abnahme der Grundwasserbelastung durch Nitrate sowie zu einer erhöhten NUE sowohl bei BP als auch bei CT. Die Bodenversalzung bei BP in den oberen Bodenschichten nahm bei EFI und ASFI signifikant zu im Vergleich zu PSFI. Letztere Methode ergab einen weniger versalzten Bereich in Richtung bewässerter Furche, weil sich das Salz in den permanent trockenen Furchen anreicherte. Diese erhöhten Salzmengen können ausgewaschen werden, wodurch die Versalzung in der Mitte zweier Pflanzbetten um ein Zweifaches reduziert wurde im Vergleich zu EFI und ASFI. Bei in Rotation angebauten Baumwolle, Weizen und Mais war BP mit Ernterückständen zusammen mit der jeweils empfohlenen N-Menge und mit ~15% unter den jeweiligen Empfehlungen liegenden N-Mengen in vielen Aspekten den CT Methoden überlegen. Anbau von Baumwolle auf erhöhten, permanenten Pflanzbetten zusammen mit einer Wintergründungung ist eine geeignete Alternative für Baumwolle- Baumwolle-Systeme in den bewässerten Trockengebieten von Usbekistan. Sollten Ernterückstände nicht verfügbar sein, ist PSFI eine geeignetes alternatives Bodenversalzungsmanagement bei BP auf versalzten bewässerten Flächen

Sustainable land management & organic amendments for crop production & restoration in drylands - ICARDA's experience

F2R-CWANA WP3 scientist Mina Devkota Wasti was invited to speak at the "The Perspective of Future Technologies for Soil Amendments" organised by the Palladium Group about the ICARDA's experience in sustainable land management, organic amendments for crop production, and restoration in the drylands (through F2R-CWANA and EiA Initiatives)

Diversifying crops improves system productivity and resilience for smallholder farmers in rainfed drylands

Diversifying crops improves system productivity and resilience for smallholder farmers in rainfed drylands

Minimum Dataset Required to Collect from Agronomic Field Experimentation

Implementing strategic field experimentation not only provide opportunities to solve the research questions but also provide a useful way to address a number of important issues in crop, soil, water, environmental and resource economics using different analytical tools. As implementing field experimentation is resource intensive (cost, time and energy), it is important to plan for collecting/generating standard data set (both quality and minimum number)

Conservation agriculture improves agronomic, economic, and soil fertility indicators for a clay soil in a rainfed Mediterranean climate in Morocco

CONTEXT: Declining rainfall with increasing variability, increasing temperature extremes, and declining soil fertility are threatening crop production and ultimately food security in the rainfed Mediterranean environment in Morocco. Conservation agriculture (CA) practices such as reduced tillage, soil cover, and appropriate crop rotation are recognized as a set of adaptive agricultural systems in such climate-sensitive regions. Systematic evaluation of agronomic, economic, and soil fertility indicators with medium-and long-term adoption of CA in different crop rotations in such variable climatic conditions is needed to drive wider adoption of CA in the region. OBJECTIVE: The objective of this study was to systematically evaluate agronomic, economic, and soil fertility indicators under CA and conventional tillage (CT) using field experimentation (medium-term) and simulation modeling (long-term) for a clay soil of a rainfed Mediterranean environment. METHODS: Methodologies included the following: 1) Field experimentation for 5 years (2015–2019), comparing CA and CT in four major food crops: wheat, barley, lentil, and chickpea, conducted in Merchouch, Morocco. The objective was to determine the effect of CA on crop productivity, yield stability, profitability, precipitation use efficiency, and soil fertility indicators of individual crops and cropping systems. (2) Dynamic simulation modeling to understand the long-term effect of adopting CA and CT under cereal–legume and cereal–cereal rotation systems. Using 5 years of experimental data, we calibrated and validated a Decision Support System for Agrotechnology Transfer (DSSAT) model for four crops; and ran the model for 36 years for two major rotations

Genotype × environment × agronomic management interaction to enhance wheat yield in the Mediterranean rainfed environments of Morocco: II. Process based modeling

urum wheat (Triticum turgidum subsp. durum) is the oldest and most cultivated cereal crop in Middle East and North Africa (MENA) region and under Mediterranean climatic conditions. Morocco is one of the largest pro ducer of durum wheat in MENA region, cultivated in more than 1 million ha area produced 2.5 million tons in 2020, which accounts for 17% of the total production in the region. In the region, rainfed production system is predominant, and with declining rainfall amounts with high variability, increasing water scarcity, and subop timal input application, its productivity growth is low and needs to be increased to fulfill the growing demand. Developing context-specific management advisory is needed to improve productivity and resilience under such variable rainfed production environments. Agricultural Production Systems sIMulator (APSIM) model was calibrated and evaluated using four years (2015–2019) of on-station experimental data from genotype × seeding time × water management experiment conducted at International Center for Agricultural Research in the Dry Areas (ICARDA) research station, Morocco. Long-term (1984–2021) simulation was carried out to determine the contribution of Genotype × Environment × Management components for sustainably improving crop produc tivity. The results showed rainfall or supplementary irrigation (23–36%) followed by N fertilizer (28–38%), cultivar (9–14%), and seeding date (7–14%) have the largest contribution to the yield variance of durum wheat in Merchouch, Meknes, and Sidi El Aidi regions of Morocco. Under rainfed conditions, wheat yield was highest in Merchouch (4.5 t ha− 1 ) and lowest (1.8 t ha− 1 ) in Sidi El Aidi. Due to significant rainfall variability, the seeding date varies across year and location; however, generally, it is between 2nd week of November to 1st week of December. Under rainfed conditions, seeding after 1st week of December caused the average yield reduction of 120, 81, and 31 kg ha− 1 d− 1 in Merchouch, Meknes, and Sidi El Aidi, respectively. In all locations, short-duration varieties provided higher averaged yields with better resilience than medium and long-duration varieties. Decomposing yield variance caused by Genotype × Environment × Management provides the opportunity for risk reduction, improvement of wheat yield and resilience, and designing climate-smart adaptation strategies in rainfed Mediterranean conditions. Our findings highlight one-size-fits-all approach is inadequate and context specific tailored agronomic practices and suitable genotypes is crucial for achieving sustainability and resil ience of wheat production in variable climatic condition in Morocco and similar production environment

Diversified Cropping System: Relay Intercropping of Lentils with Chickpeas [Morocco]

A Diversified Cropping System (DCS) results in a more resilient and productive cropping system. In this case, chickpeas were introduced as a relay intercrop between established lines of lentils. This not only had no negative effect on lentil yields, but also enabled the harvest of an extra crop: chickpeas

Managing salinity for sustainable agricultural production in salt-affected soils of irrigated drylands

CONTEXT Declining water quantity and quality and poor land, water, and crop management practices are leading to increasing soil salinity, land degradation, desertification, and threatening the overall sustainability of the crop production system in irrigated drylands. Assessments of salinity dynamics and sustainability indicators under alternative agricultural practices are needed to identify the right combination of practices that improve sustainability while minimizing land and environmental degradation. OBJECTIVE The objective of this study was to assess the potential of conservation agriculture (CA)-based practices, water-saving irrigation, water quality, and nitrogen (N) fertilizer rates for improving the sustainability of rice-wheat (RWS) and cotton-wheat (CWS) systems in salt-affected irrigated drylands. METHODS The study included mixed-method approaches of two years of field experiments, soil profile and groundwater salinity simulation using Hydrus-1D model, and multi-criteria trade-off analysis for the holistic assessment of alternative innovations in RWS and CWS. The treatments in experiments were composed of a combination of CA-based practices, water-saving irrigation and N rates. Fourteen sustainability indicators computed from experiments and simulation were compared to evaluate the sustainability of those cropping systems and to reveal the potential of those practices for improving sustainability. RESULTS AND CONCLUSIONS Compared to the initial conditions, the soil salinity decreased in both cropping systems, while the reduction rate was much higher in RWS than CWS (by 28%). In RWS, the conventional treatment had the lowest salinity level, while in CWS, CA (permeant bed + residue retention) had the lowest. RWS raised the groundwater table by 25% compared to CWS. The long-term scenario analysis with Hydrus-1D demonstrated that, with increased irrigation water salinity and soil evaporation rates, soil profile salinity increases by 78% in RWS and 66% in CWS. RWS had a higher net profit (+81%) and soil organic carbon (SOC) (-15%), but lower water productivity (WP) (−147%), nitrogen, and energy use efficiency (EUE) (−46%) than CWS. The CA-based practices in CWS improved sustainability indicators with higher yield and net profit (+20%), WP (+26%), SOC (+456%), and EUE (36%) with decreased soil salinity than in the conventional system

Why Conservation Agriculture in rainfed drylands in Morocco

Crop yield in the rainfed Mediterranean environment in Morocco, the hot spot for climate change, is highly affected by rainfall variability, temperature extremes, and declining soil quality. Several research findings reported that Conservation agriculture (CA) has potential to minimize climatic risk, reduce soil erosion, and improve water use efficiency and soil health compared to conventionally tilled (CT) field in such climatic condition

Potential of Crop Simulation Models to Increase Food and Nutrition Security Under a Changing Climate in Nepal

With current trends of increasing population, decreasing arable land, and a low yearly increment rate of cereal productivity, Nepal has an annual deficit of >1.3 million tons of edible rice, wheat, and maize. This indicates the urgent need for demand-led agricultural interventions for improving cereals productivity for food security. Crop simulation models and DSS tools have potential to predict potential yields, identify yield gaps, and help make decisions for improved crop, nutrient, water and pest management. Models can assess the impact of climate change, and help develop adaptation and mitigation measures to lesses the impact of climate change. To date, no review work has been conducted on the potential applications of crop simulation models and their relevance in Nepal. The objective of this chapter is to review and synthesize the relevant studies on the development and application of crop simulation models for major cereal crops: rice, wheat, and maize. We reviewed around 95 published papers and reports from South Asia and Nepal available in Scopus, SpringerLink, and ScienceDirect using the Google search engine. Analysis revealed that yield gaps (potential minus farmers' field yields) of 4.9–9.0, 3.1–6.9, and 4.5–12.5 t ha−1 exist in rice, wheat, and maize crops, respectively. For achieving self-sufficiency in cereal grains, the average national productivity of rice, wheat, and maize needs to be increased to 5.7, 3.9, and 4.9 t ha−1, respectively by 2030. Based on the review, climate change has both positive and negative consequences on cereal production across all agro-ecological zones. Crop simulation models have been applied for enhancing crop productivity and exploring adaptation strategies for climate change resilience. Models can generate various recommendations related to biophysical factors: crop, water, tillage, nutrient, and pest management, crop yield, and weather forecasting. Furthermore, models have shown the potential to determine the effects of climate change on crop productivity across a range of environments in Nepal. In conclusion, crop simulation models could be useful decision support tools for policy planning and implementation, increasing efficiency in research, prioritizing research and extension interventions for increasing crop yields, and the way forward to achieve food and nutritional security and some of the Sustainable Development Goals (particularly #1, #2 and #13)