Rainfed Farming Systems Research Articles

Ecological conservation, biodiversity, and agricultural education as integrated approaches for envisioning the future of sustainable agriculture in North America

ABSTRACT In the ancestral heritage, mankind was in mutual interdependence with nature through hunting of animals, gathering of plant materials, and animal and plant domestication. However, agricultural advancements detached mankind from that heritage. In U.S. Midwest, it is evident that technological advancements over the past half-century have threatened man’s survival for centuries to come. Midwest is the prime agricultural land area in North America whose recent glaciation, deep-rooted prairie vegetation, and moderate precipitation favored the development of highly productive rain-fed farming systems. Evolution of productionist paradigm in Midwest focused on crop and livestock output but also resulted in numerous environmental externalities. Massive use of agrochemicals, for instance, resulted in pollution of Mississippi River watershed from upperstream to downstream creating a hypoxic zone in Gulf of Mexico. In this situation, it is appropriate to ask what best alternatives for mankind could be to reconnect with nature to achieve sustainability. The study explored three approaches including ecological conservation, biodiversity, and agricultural education. Conservation requires the passion of humanity to reconnect with ecological community and become part of it rather than to manipulate and seek control over it to reap ecosystem services. In creating interrelated diversity through domestication of culturally important wild species, agroforestry, horticulture, animal husbandry, and inclusion of relevant language and culture we can define a sustainable world. Agricultural education brings in three tenets of teaching/learning, research/discovery, and extension/engagement to provide, create, and apply knowledge, respectively, which are important in communicating the science of sustainability.

Vulnerability of crop water footprint in rain-fed and irrigation agricultural production system under future climate scenarios

Agriculture is the sector most sensitive to climate change. It is of great significance to explore the response characteristics of crop water footprint (WF) in rain-fed and irrigation agriculture to climate change for guiding agricultural production. This study coupled and downscaled the meteorological data from 31 global climate models (GCMs) under two Representative Concentration Pathways (RCPs) in China, and used crop growth model AquaCrop in large scale to quantify the changes in yield and WF of maize in China from the 2030s to the 2090s. The Monte Carlo Method was used to calibrate the crop parameters in AquaCrop model, which improved the accuracy and spatiotemporal resolution of the crop model. Results showed that precipitation and temperature would increase in most regions in China, which was more obvious in the RCP8.5 scenario. Meanwhile, climate change resulted in larger crop evapotranspiration (ETc) for maize in the north than south. In the future, the increase of ETc in Southwest China would be relatively larger, while that in Northwest China would decrease. Maize yield would generally increase in most regions except for central China, where illustrated that increases in the north was greater than in the south. In terms of irrigation strategies, full irrigation could mitigate the reduction in maize yield caused by climate change. However, increasing irrigation would have fewer benefits to maize yield in humid regions compared with arid and semiarid regions in China. In addition, increasing irrigation could not greatly reduce the WF of maize in humid regions. Due to different climatic and hydraulic soil characteristics in each region, the effects of climate change and irrigation strategies on WF of maize would vary in different regions. This study provided irrigation strategies guidance to mitigate the adverse effects of climate change on agricultural production and its water use.

Rainwater harvesting and water balance simulation-optimization scheme to plan sustainable second crop in small rain-fed systems

Environmental degradation in the form of water shortage and uncertainty has severely affected the food systems across the globe. Especially in India, which is dominated by rain-fed farmers, the need for sustainable water resource and its management at farm level is imperative for farming livelihoods and food security of the country. Rainwater harvesting in on-farm reservoirs (OFR) can enable crop diversification, year round cropping and seasonal vegetable cultivation in rain-fed farming systems in India. However appropriate sizing of OFR remains a serious concern especially for small and marginal farmers with limited land holdings. In this study, a novel and comprehensive simulation-optimization model was developed to determine the optimal size and utilization of OFR. The simulation consisted of water balance of soil and OFR using hydrological analysis for last 28 years, through which supplement irrigation needs and, rainwater harvesting potential was estimated. Optimal use of available water in OFR was designed using a multi-stage process wherein the model generated, compared and screened appropriate vegetable plans for Rabi cultivation. The model was simulated for different OFR sizes and the optimal size was chosen based on its economic feasibility. To demonstrate the model, a case study was simulated wherein high supplement irrigation was estimated, indicating a severe limitation in rain-fed farming. A minimum OFR size of 9.9% of the total land was required. With an increase in OFR sizes, the profits increased however, the growth rate declined as the cropping area was reduced. An OFR size of 15.5% of total land was found to be optimal which gave benefit-cost ratio and payback period of 2.4 and 6.8 years respectively. Trends in cultivation plans for different sizes of OFR was observed wherein for small OFR sizes, the model generated fewer options of cultivation plans and preferred crops with high water productivity over crops with high profitability. The proposed model is generic and applicable at multiple scales and scenarios. The model could be used by environmental decision makers, farm managers, policy makers and researchers to determine the feasibility of any water resource intervention using an ecosystem centric approach when multiple scenarios of cultivation are possible.

Identification of Summer Monsoon Onset over Nepal by using Satellite-Derived OLR Data

Summer monsoon onset is considered as the beginning of the rainy season in South Asia. In Nepal, summer monsoon onsets from eastern part and ~80% of the annual rainfall occurs during summer monsoon season (i.e., June to September). The monsoon onset is one of the crucial elements for the socio-economic development as the majority of the population depends primarily on rain fed agriculture systems for their livelihood. For identification of the monsoon onset date over eastern Nepal, daily mean satellite-derived Outgoing Long-wave Radiation (OLR) data (10 × 10 spatial resolution) obtained from National Environmental Satellite Data and Information Service (NESDIS), NOAA is used. Long term OLR data from 1979 to 2019 for March to June is analyzed to study monsoon progression towards eastern Nepal. The rainfall amount obtained from rain gauge stations is compared with the OLR data, which depicts a higher correlation in the southern part of Eastern and Central Nepal than in the northern regions. A convective episode signifies the drop in OLR by about 45 Wm-2 from 10 May to 10 June. Further, the relation between the date of characteristic fall of OLR below 250Wm-2 and monsoon onset date announced by MFD (Meteorological Forecasting Division) for the study period is evaluated to predict new onset dates over the region. The predicted onset date is found as 13th of June on average and its correlation with the MFD onset date is 0.6 (p<0.01). The study highlights the potential application of the satellite-derived OLR based method for the early prediction of onset of summer monsoon over eastern Nepal.

Impacts of Climate Smart Agriculture Practices on Soil Water Conservation and Maize Productivity in Rainfed Cropping Systems of Uganda

With climate change, maize production is becoming more constrained by limited water availability especially in rainfed production systems. Climate Smart Agriculture (CSA) practices have potential to enhance water availability and water use efficiency in rainfed production systems, but their efficiencies have not been adequately investigated. The study evaluated the performance of permanent planting basins (PPB), mulching (M), and halfmoon pits (HM) on soil moisture storage, maize yield, and water use efficiency in a maize cropping system for the sub-humid areas of Uganda for three cropping seasons in Albert region. The control treatment consisted of bare soil as the existing conventional farming practice without any CSA practice. Maize growth parameters and soil moisture storage were monitored and evaluated in each cropping season and CSA treatment. The maize yield, water use efficiency, and evapotranspiration (ET), were determined in each CSA treatment. Results showed that CSA practices significantly increased (P < 0.05) total soil water storage (1–12%) than the control treatment. It was also noted that; the use of M, PPB, and HM increased the water use efficiency by 9 – 68% and 8 – 66% of grain yield compared to the control in the three growing seasons. Our results indicate that even under unreliable and limited precipitation in sub-humid regions, the studied CSA practices indicate a high possibility to increase maize productivity than conventional farming practices (control). These findings are critical as climate change continues to affect maize productivity in rainfed farming systems where there limited supplemental water alternative sources for smallholder farmers. The adoption of CSA practices will enhance the resilience of maize production in sub-humid regions.

Assessment of the Impact of Rainfall Variability and Vegetable Production in Bamenda III Sub-Division, Cameroon

Climate variability has a direct bearing on agricultural production. The relationship between temperature and rainfall provides ideal conditions for the development of crops in rain-fed agricultural systems. This is patent in predominantly rain-fed vegetable production exposed to rainfall variability. This study assesses the impact of rainfall variability on vegetable production in Bamenda III Sub-Division. The data on rainfall was collected for 54 consecutive years (1963–2017) and analysed using Rainfall Anomaly Index to determine the Inter-Annual Rainfall Anomalies. This was to determine the extent of rainfall variability impacts on vegetable production. Results revealed a reliable but fluctuating periodical rainfall rates with highest positive and negative anomalies of +60mm and -55mm respectively. With a Standardized Precipitation Index of 0.41, there was evidence of an increasing trend in decadal rainfall and positive trend on conditions for vegetable cultivation. The high variability of rainfall is associated with a reduction in vegetable production output. Such rainfall variability plays a major role in vegetable production which is generally rain fed. The study posits that stakeholders’ responsive adaptation options in cropland management for vegetable production in the phase of rainfall variability are credible in reversing the increasing negative impact of rainfall variability in the context of climate change.

Reap when you sow? The productivity impacts of early sowing in Malawi

CONTEXTThe timely sowing of groundnut is a crucial management practice for attaining higher productivity in rainfed farming systems as is the case in Malawi. However, much of the evidence comes from agronomic field trials that present different production conditions than those faced by farmers. OBJECTIVEWe exploit variation in groundnut sowing dates on actual farmer plots in central Malawi to evaluate technology and technical efficiency (TE) gaps, and frontier yield differentials associated with early sowing. METHODSWe address bias from observables through statistical matching and from unobservables through the selectivity-corrected stochastic production frontier (SC-SPF) model. A semi-parametric stochastic metafrontier (SMF) technique is then applied to address technology differences and TE comparisons. RESULTS AND CONCLUSIONSThe SC-SPF and SMF frameworks are both supported by the data, and early sowing leads to larger gains in output through an outward shift in the production frontier, suggesting better access to the best practice technology. Farmers that sow early also exhibit higher managerial performance. Productivity gains are enjoyed by various groups such as male and younger farmers, and those with exposure to supply driven agricultural extension. SIGNIFICANCEThe findings provide clear support to early sowing as an attractive option for smallholder productivity enhancement and higher food security. Results lend strong empirical evidence of the benefits of early sowing in Malawian groundnut farming.

Breeding Drought-Tolerant Pearl Millet Using Conventional and Genomic Approaches: Achievements and Prospects.

Pearl millet [Pennisetum glaucum (L.) R. Br.] is a C4 crop cultivated for its grain and stover in crop-livestock-based rain-fed farming systems of tropics and subtropics in the Indian subcontinent and sub-Saharan Africa. The intensity of drought is predicted to further exacerbate because of looming climate change, necessitating greater focus on pearl millet breeding for drought tolerance. The nature of drought in different target populations of pearl millet-growing environments (TPEs) is highly variable in its timing, intensity, and duration. Pearl millet response to drought in various growth stages has been studied comprehensively. Dissection of drought tolerance physiology and phenology has helped in understanding the yield formation process under drought conditions. The overall understanding of TPEs and differential sensitivity of various growth stages to water stress helped to identify target traits for manipulation through breeding for drought tolerance. Recent advancement in high-throughput phenotyping platforms has made it more realistic to screen large populations/germplasm for drought-adaptive traits. The role of adapted germplasm has been emphasized for drought breeding, as the measured performance under drought stress is largely an outcome of adaptation to stress environments. Hybridization of adapted landraces with selected elite genetic material has been stated to amalgamate adaptation and productivity. Substantial progress has been made in the development of genomic resources that have been used to explore genetic diversity, linkage mapping (QTLs), marker-trait association (MTA), and genomic selection (GS) in pearl millet. High-throughput genotyping (HTPG) platforms are now available at a low cost, offering enormous opportunities to apply markers assisted selection (MAS) in conventional breeding programs targeting drought tolerance. Next-generation sequencing (NGS) technology, micro-environmental modeling, and pearl millet whole genome re-sequence information covering circa 1,000 wild and cultivated accessions have helped to greater understand germplasm, genomes, candidate genes, and markers. Their application in molecular breeding would lead to the development of high-yielding and drought-tolerant pearl millet cultivars. This review examines how the strategic use of genetic resources, modern genomics, molecular biology, and shuttle breeding can further enhance the development and delivery of drought-tolerant cultivars.

ADAPTATION STRATEGIES OF JHUM CULTIVATORS TOWARDS CLIMATE CHANGE IN MOKOKCHUNG DISTRICT, NAGALAND

In the recent years, the impact of climate change for Jhum cultivators has been very apparent as jhum cultivation is purely a rain-fed agricultural system and crop production can be extremely sensitive to year-to-year weather fluctuations. The present investigation was conducted in Ongpangkong block of Mokokchung district of Nagaland. A total number of 120 respondents from 4 villages were selected using proportionate random sampling procedure. Data was collected through pre structured interview schedule and processed through primary and secondary tables and statistical analysis. The study revealed that the overall adaptation practices towards climate change were medium. Age, farming experience, extension contacts, mass media exposure and social contact were positively significant with the adaptation level towards climate change.

Determinants of Farmers’ Awareness and Adoption of Extension Recommended Wheat Varieties in the Rainfed Areas of Pakistan

Scientific evidence suggests that there is room for eradicating poverty and hunger by increasing food production through the adoption of modern agricultural practices by farmers. This study aimed, first, to explore the relationship between the farmers’ awareness and adoption of improved wheat varieties. Second, it aimed to find the key factors that govern the farmers’ awareness and adoption of extension-recommended innovations in the rainfed cropping system of the Khyber Pakhtunkhwa, Pakistan. Data were collected from 395 respondents. A binary logit model was used to analyze the effect of the farmers’ socioeconomic and farm-specific characteristics on their awareness and adoption of the extension-suggested wheat varieties. Moreover, qualitative data from 40 key informants were collected for in-depth analysis. The results show a strong association between the farmers’ awareness of a technology (improved wheat varieties) and its adoption. The results of the logit model show that their extension contacts, income from agriculture, and access to credit positively affected the farmers’ awareness, whereas their education and household sizes negatively affected their awareness. Moreover, the factors that positively influenced the farmers’ decision to adopt the technology included the extension contact, the confidence in the extension, the risk-bearing attitude, and the credit access, whereas the household size and education negatively affected it. The results of the key informant interviews reveal that the high incidence of poverty, the low soil fertility, the farmers’ inability to make effective decisions, the lack of accurate weather predictability in the rainfed farming system, the lack of government interest, and the asymmetric information in the inputs markets contributed to the farmers’ low levels of awareness and to their poor adoption of improved agricultural technologies. These results indicate that any intervention aimed at the awareness and adoption by farmers of improved technologies, such as new wheat varieties, should recognize the heterogeneity in the farmers’ socioeconomic and farm-specific characteristics.

Optimum fertilizer application rate to ensure yield and decrease greenhouse gas emissions in rain-fed agriculture system of the Loess Plateau

Application of nitrogen (N) can increase the supply of N in soil and, in turn, can lead to higher yield—but also to large increase in emissions of greenhouse gases (GHGs) if applied in excess. To determine the optimum dose of N for maize planting system, we analysed the relationship between yield and emissions of GHGs at seven levels of N, namely 50, 100, 150, 200, 250, 300, and 350 kg ha−1, using the DNDC (denitrification decomposition) model and maize grown with and without mulching. The model simulated the following variables: maize production; emissions of carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4); global warming potential (GWP); and GHG intensity (GHGI). We used data from 1980 to 2013 for a rain-fed region of the Loess Plateau in north-western China and validated the DNDC model against data from field experiments. The model performed well in simulating yield and GHG emissions (Adj.R2 > 0.61). Under mulching, the average yield of maize was 3.6–12.2 t ha−1 and the partial factor productivity was 73.1–35.0 kg kg−1; and both of these were significantly higher 78%–236% than those in the crop without mulching. The emissions of CO2, N2O, and the GWP increased with the increase in the dose of N whereas CH4 emissions remained unaffected by the dose. Mulching increased yields significantly in the north-western region, and the GWP and GHGI were higher mainly in the central and north-western regions. The optimum dose of N for maize grown with mulching ranged between 150 kg ha−1 and 200 kg ha−1 and offers the best balance between higher yield and lower emissions. The optimum dose may promote the development of mulched maize and provide a reference standard for dryland agriculture in zones with similar climates elsewhere in the world.

Water use efficiency in Western Australian cropping systems

Rotations and associated management practices in rainfed farming systems of southwest Australia have shifted towards intensified cropping. Survey data from 184 fields spanning 14 Mha of southwest Australia were used to document water use efficiency (WUE) and water-limited yield potential (WLYP) of commercial crops and crop sequences and identify biophysical variables influencing WUE. WUE achieved in commercial wheat crops was 10.7 kg grain/ha.mm. Using a boundary function Ywl = 25 × (WU − 45), farmers achieved 54% of WLYP. Climate variables affected WUE more than management and biotic variates, the highest latitude region having WUE of 9.0 kg grain/ha.mm, compared to 11.8 kg grain/ha.mm for regions further south. Increased soil nitrogen and nitrogen fertiliser increased WUE, as did sowing earlier; in keeping with farmers in southern Australia sowing crops earlier and trebling fertiliser nitrogen usage since 1990. Wheat yield and WUE increased a small amount after break crop or pasture (12.5 kg grain/ha.mm) compared to wheat grown after wheat (11.2 kg grain/ha.mm), due to good weed and root pathogen control, and high fertiliser nitrogen application. However, WUE of wheat declined to 8.4 kg grain/ha.mm when more than three wheat crops were grown in succession. Farmers continue to improve WUE with increased inputs and new technologies replacing some traditional functions of break crops and pasture. However, break crops and pastures are still required within the rotation to maintain WUE and break effects need to be measured over several years.

Links between soilborne pathogens, plant parasitic nematodes, farm management and biophysical constraints in a southern Australian rainfed cropping system

Context Rotations in rainfed farming systems of southwest Australia have shifted towards intensified cropping and it is necessary to reassess soilborne pathogens and plant parasitic nematodes within this context. Aims We tested the hypothesis that these recent changes in rotations and agronomy have altered the efficacy with which rotations reduce the incidence of common root pathogens and plant parasitic nematodes. Methods We tracked changes in common pathogen DNA in soil and the incidence and severity of crop root damage in 184 paddocks, over 6 years from 2010 to 2015, and related this to farmer practices. Key results Overall, severe root damage was rare, with 72% of plant samples showing no damage or only a trace and only 1% severely damaged. We found that the reduction of paddocks in pasture and resultant very low weed populations, combined with early sowing, reduced persistence of pathogens and nematode pests. But some aspects of crop management had the opposite effect: high rates of herbicide, increased frequency of cereals and canola at the expense of lupin and increased N fertiliser use. Conclusions Current agronomic practices and the frequency of non-host crops in rotations appear to be effective in controlling common root pathogens and plant parasitic nematodes. But the aspects of agronomic management that increased populations of pathogens should be applied cautiously. Implications Studies such as this that link multiple productivity constraints, such as pathogens and nematode pests, weeds and nutrients, to management practices are important to understand the sustainability of current or proposed production methods.

Yield of Rainfed Finger Millet under Selected Agronomic Practices: A Study in Southern Dry Zone

The farmers in Southern dry zone in Sri Lanka are cultivating finger millet mostly under rainfed condition and majority of them practice random broadcasting for crop establishment. The yield obtained by the conventional rainfed farmers is considerably lower. Already there are available a number of improved low cost approaches can enhance the yield in a sustainable manner but such techniques are not used by the farmers in the rainfed farming systems. This study was carried out to enhance the finger millet yield by introducing some agronomic practices with a high yielding variety (Rawana), row seeding in 30 cm spacing, application of half of basal fertilizers recommended by Department of Agriculture (DOA) in Sri Lanka, with compost at the rate of 2 Mg ha-1 and practicing two weeding at third and sixth weeks from planting. Sustainable Agronomic Package of Practices (SAPP) was developed during 2014/2015 and 2015/2016 Maha seasons. Then farmer field demonstrations were conducted during 2016/2017 and 2017/2018 Maha seasons and developed SAPP was compared with traditional farmer practice. Results revealed that the yield can be increased by 165% to 182% by following SAPP with transplanting and sowing at 30 cm spacing compared to the yield to the farmer practice and it was 200% and 220% respectively compared to the estimated average finger millet yield of 1.3 Mg ha-1 in Sri Lanka.

Assessment of spatiotemporal trend of precipitation indices and meteorological drought characteristics in the Mahi River basin, India

Understanding the trend and variability in hydroclimatic extremes as well as drought characteristics in the context of changing climate is of paramount importance in the management of watershed and rain-fed farming systems. This study focuses on understanding the variations in rainfall patterns & drought types with 3 regions of the agro-climatic zone, in the Mahi River basin, India. The basin is surrounded by three states i.e. Rajasthan, Madhya Pradesh, and Gujarat which is known for its substantial drought occurrences. Very limited studies have been carried out using agroclimatic indices. A 50 years of daily rainfall data (gridded, 0.25°×0.25° spatial resolution) from 1970 to 2019 has been taken from India Meteorological Department (IMD) to compute extreme precipitation indices using ClimPACT2 package and time series trend was tested by Mann-Kendall. Further, 51 grid points are divided into three regions (region 1, region 2, and region 3) as per the agro-climatic zones over the Mahi River basin. The region-wise agroclimatic rainfall variability has been analyzed using monthly standard deviation and anomaly index. The run theory was applied for the characterization of drought assessment. Standardized precipitation index (SPI) was performed for 3, 6, 12, and 24-months. The result found a Consecutive dry day (CDD) with increasing trend significantly and Consecutive wet days (CWD) with decreasing trend may cause a possible impact on agriculture. Findings revealed that region 2 recorded consequent frequent and maximum droughts events over the basin. Hence, the regional topography and moisture availability perform a major role in regional precipitation variability. The output of the current study would be utilized in a better understanding of the drought condition and give a better climate change indication at a regional-basin level. This finding may be valuable for researchers to find out the crucial agro-climatic regions in the basin for preparedness for effective management and planning of water resources.

Trends of Rainfall Onset, Cessation, and Length of Growing Season in Northern Ghana: Comparing the Rain Gauge, Satellite, and Farmer’s Perceptions

Rainfall onset and cessation date greatly influence cropping calendar decisions in rain-fed agricultural systems. This paper examined trends of onsets, cessation, and the length of growing season over Northern Ghana using CHIRPS-v2, gauge, and farmers’ perceptions data between 1981 and 2019. Results from CHIRPS-v2 revealed that the three seasonal rainfall indices have substantial latitudinal variability. Significant late and early onsets were observed at the West and East of 1.5° W longitude, respectively. Significant late cessations and longer growing periods occurred across Northern Ghana. The ability of farmers’ perceptions and CHIRPS-v2 to capture rainfall onsets are time and location-dependent. A total of 71% of farmers rely on traditional knowledge to forecast rainfall onsets. Adaptation measures applied were not always consistent with the rainfall seasonality. More investment in modern climate information services is required to complement the existing local knowledge of forecasting rainfall seasonality.

Simulation of soil water balance and crop productivity of long-term continuous maize cropping under high planting density in rainfed agroecosystems

Increasing planting density is one of the main management practices contributing to maize grain yield improvements across the world, but the soil water sustainability after long-term continuous high-density under rainfed farming systems is not clear. Crop simulation models may help explore suitable management systems for increasing crop productivity and economic benefits. The present study calibrated and validated the DSSAT-CERES-Maize model in a four-year field experiment, which coupled four densities from 52,500 to 97,500 plant ha−1 and two cultivars under rainfed conditions. The calibrated CERES-Maize model performed fairly well in simulating the phenological dates, and the average root mean-squared error (RMSE) ranged from 0.7 to 2.8 d for anthesis and 0 to 2.8 d for maturity date. The normalized root mean squared errors (nRMSE) for biomass and grain yield were 17.5% and 12.4%, respectively. The average nRMSE for soil water dynamics in the 0–200 cm soil layers was 15.6% among the different growth stages. The calibrated model was subsequently used to evaluate the soil water regime and crop productivity in response to planting density under 38 years of meteorological data. The results showed that maize water productivity and evapotranspiration (ET) fluctuated with seasonal rainfall, and normal and wet years were significantly higher than dry years. Although ET during the growing season tended to increase with increasing density, the long-term continuous high planting density did not cause excessive soil water consumption. Grain yield and water use efficiency (WUE) tended to exhibit a parabolic relationship with planting density during the long-term simulated seasons between different experimental sites. No significant differences were detected between different cultivars in water productivity under long-term simulation. However, the simulation results suggested that the optimal planting density was often related to variability in climate conditions between sites and years. The scenario simulation results suggest that the optimal density should not exceed 67,500 plant ha−1 when the annual precipitation is less than 500 mm, but it should not exceed 82,500 plant ha−1 in areas where the rainfall is greater than 500 mm. Therefore, this study suggests that moderate planting density has the potential to realize sustainable maize development in dryland farming systems on the Loess Plateau and similar areas.

Optimum Planting Density Improves Resource Use Efficiency and Yield Stability of Rainfed Maize in Semiarid Climate.

Increasing planting density is an effective strategy for improving maize productivity, but grain yield does not increase linearly with the increase in plant density, especially in semiarid environments. However, how planting density regulates the integrated utilization of key input resources (i.e., radiation, water, and nutrients) to affect maize production is not clear. To evaluate the effects of planting density and cultivar on maize canopy structure, photosynthetic characteristics, yield, and resource use efficiency, we conducted a successive field experiment from 2013 to 2018 in Heyang County (Shaanxi Province, China) using three different cultivars [i.e., Yuyu22 (C1), Zhengdan958 (C2), and Xianyu335 (C3)] at four planting densities [i.e., 52,500 (D1), 67,500 (D2), 82,500 (D3), and 97,500 (D4) plants ha–1]. Increasing planting density significantly increased the leaf area index (LAI) and the amount of intercepted photosynthetically active radiation (IPAR), thereby promoting plant growth and crop productivity. However, increased planting density reduced plant photosynthetic capacity [net photosynthetic rate (Pn)], stomatal conductance (Gc), and leaf chlorophyll content. These alterations constitute key mechanisms underlying the decline in crop productivity and yield stability at high planting density. Although improved planting density increased IPAR, it did not promote higher resource use efficiency. Compared with the D1 treatment, the grain yield, precipitation use efficiency (PUE), radiation use efficiency (RUE), and nitrogen use efficiency (NUE) increased by 5.6–12.5%, 2.8–7.1%, and −2.1 to 1.6% in D2, D3, and D4 treatments, respectively. These showed that pursuing too high planting density is not a desirable strategy in the rainfed farming system of semiarid environments. In addition, density-tolerant cultivars (C2 and C3) showed better canopy structure and photosynthetic capacity and recorded higher yield stability and resource use efficiency. Together, these results suggest that growing density-tolerant cultivars at moderate planting density could serve as a promising approach for stabilizing grain yield and realizing the sustainable development of agriculture in semiarid regions.

Formulation of biofertilizer for improving growth and yield of wheat in rain dependent farming system

Low and erratic rainfall can cause a significant reduction in crop yields in agriculture systems that rely exclusively on rain water. Some plant growth promoting rhizobacteria (PGPR) capable of producing 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase can mitigate the negative impact of water stress on plant in rainfed agriculture through modulation of plant stress hormone ethylene. The present study was conducted in rainfed areas to demonstrate the potential of PGPR with ACC-deaminase activity to enhance the growth and yield of wheat ( Triticum aestivum L.) under field conditions. Previously isolated bacterial strains ( Serratia odorifera CC7, Aerococcus viridans CK3 and Serratia proteamaculans R20) having in-vitro ACC deaminase activity were used for inoculation. Peat, compost and biochar were used as carrier material for the formulation of biofertilizer. Our results show that application of the compost biofertilizer increased plant biomass up to 27% and grain yield up to 33.3% compared with uninoculated control. Maximum N and P content in grain was observed 24.7 % and 25.8% respectively. Maximum ACC-deaminase activity of 821 nmol g −1 biomass h −1 was observed with strain CC7, while root colonization activity was also highest in case of strain CC7 i.e 6.2 × 10 6 compared to other strains. All the strains showed positive response to phosphate solubilization activity as well. Furthermore, ACC deaminase gene isolated from CC7 strain showed 79.1% homology to the ACC deaminase gene of Achromobacter , 83.9% homology to the ACC deaminase gene of Pseudomonas . These findings indicate that PGPR isolated from rainfed area can be used for biofertilizer formulation which could be very effective to increase the production of wheat in rainfed agriculture system. • PGPR isolated from rainfed areas can be used for biofertilizer formulation for increased yield of wheat. • Peat, compost and biochar were used a carrier material for formulation of biofertilizer. • Compost based biofertilizer increased the growth and yield of wheat under natural conditions. • The N and P content of the wheat grain increased upon use of compost biofertilizer.

EVALUATION OF RAINFED AGRICULTURE MANAGEMENT PRACTICES AS AN APPROACH FOR SUSTAINABILITY IN NORTHWESTERN COAST (NWC), EGYPT

Sustainable development can be possible in rainfed agriculture by integrated approach of soil management measures. Soil quality in the form of a quantitative index is used as an indicator of environmental quality and sustainability. Twelve farms selected to achieve the targets of the present investigation (six farms under traditional rainfed agriculture system and six farms under rainfed with supplemental irrigation) at Northwestern Coastal Zone (NWCZ). These farms varied in land use and management practices concerning fertilization practices, tillage system, crop type and cultivated period. This study selected some soil indicators vis-à -vis soil physicochemical properties of the selected farms of studied areas at NWCZ. The rating of soil quality index (SQI) and relative of soil quality (RSQI) values in this study were higher towards to rainfed agriculture with supplement irrigation farms than in traditional rainfed farms. In addition, most of the values of soil quality change (∆RSQI) were moderately increase (class II) and most of these farms were under traditional rainfed management. The results of cumulative rating index CRI showed a negative correlation and significant relationship with RSQI (R2=0.82, p<0.05). concerning the impacts of soil quality on productivity, the relationship between relative yield (Ry %) and RSQI was positive significant correlation (R2=0.78, p<0.05). Also, CRI showed negative significant correlation with Ry% (R2=0.81, p<0.05). Moreover, the highly soil quality class I, highly sustainability, low changes in soil quality and highly crop yield observed was in the farms under rainfed with supplemental irrigation system and good fertilization practices (NPK+organic manure). So, this study recommended to expansion rainfed with supplemental irrigation management system and add suitable dose of NPK application with manure along scientific lines to encourage crop yields that can be achieved on a sustainable basis, but it need a long time to reach class I quality and highly sustainable status.