Dryland Agroecosystems Research Articles

Dinamika dan Struktur Pendapatan Rumah Tangga Perdesaan di Berbagai Agroekosistem di Indonesia

<p>Agricultural development has an impact on the structural changes of the rural economy, as reflected in the changes of household income. The changes reflects the agricultural transformation which the direction and magnitude vary among ecosystems. Objective of this research was to analyze the dynamics of household income structure based on land tenure and agroecosystem. The study used panel data of Patanas (2007-2018) in eight provinces with three points of observation. Data was analized using the statistics and qualitative descriptive methods. Results of this study showed that household income, share of agriculture to total household income, and income structure changes were influenced by agroecosystem and land tenure. The largest income inequality was found in the vegetable dryland agroecosystems. Based on this study, it is recommended that to increase rural households’ income in each agroecosystem, among others, are through infrastructure development to facilitate the flow of agricultural products to the markets, employment creation through development of small and medium scales of agricultural based industry in the rural region, and increasing rural workforce skills to improve their access on employment opportunities in the agricultural and non-agricultural sector.</p>

Ridge-furrow configuration significantly improves soil water availability, crop water use efficiency, and grain yield in dryland agroecosystems of the Loess Plateau

The ridge-furrow rainfall harvesting system (RFRHS) is an in-situ rainfall collection and utilization technique that has been widely adopted in global arid and semiarid farming areas because of its significant benefits to soil water availability and crop yield. However, the integrated effects of different ridge-furrow configurations on rainwater collection and crop performance are still lacking. Using a specialized database drawn from field experiments in the Loess Plateau, we examined the regional effects of three typical ridge-furrow configurations, namely high (>1:1), uniform (=1:1), and low (<1:1) ridge-furrow ratios, on soil water storage, crop water use efficiency (WUE), and grain yield. The high ridge-furrow ratio achieved the greatest improvements in soil water storage than the other two ratios. Compared with traditional flat planting without ridge-furrow configuration, crop yield and WUE were significantly increased by 37.65%, 27.12%, 31.70%, and 47.70%, 30.00%, and 17.80% under high, uniform, and low ridge-furrow ratios, respectively. Improvements in crop yield and WUE due to the different ridge-furrow configurations were jointly affected by climate, soil organic matter, and fertilizer application. The mean annual precipitation of 600 mm and the mean annual temperature of 12 ℃ can be used as the threshold for selecting the ratio of ridge–furrow. An increase in soil organic matter gradually declined the increase in grain yield and WUE owing to the three ridge–furrow ratios, such that the maximum effect was found for the high ridge–furrow ratio. Among the three ratios, the improvements in crop yield and WUE were most notable when the application rates of nitrogen and phosphorus fertilizer were 100–200 kg ha−1 and 101–125 kg ha−1, respectively. This study examined the scientific basis of a ridge–furrow farming practice for enhancing rainfall use and crop WUE; thus, these results offer novel insights for the optimized design of a ridge–furrow ratio in dryland agroecosystems of the Loess Plateau by taking into account site-based climatic conditions, soil fertility, and fertilization input level.

Irrigation and fertilization effects on arbuscular mycorrhizal fungi depend on growing season in a dryland maize agroecosystem

Arbuscular mycorrhizal (AM) fungi form mutualistic associations with most terrestrial plants and can enhance crop water and nutrition acquisition. It is thus important to elucidate the interactive impacts of water and fertilizer management on AM fungi for sustainable agriculture. Our study investigated the effects of irrigation (well-watered vs. drought) and fertilization (nitrogen (N), phosphorus (P), and NP) on AM fungi in soil and roots of maize (Zea mays L.) across three consecutive growth phases (jointing, tasseling, and mature). Drought significantly decreased AM fungal extra-radical hyphal density and root colonization rate at the tasseling and mature phases, respectively. Nitrogen and NP fertilization exerted a negative effect on AM fungal spore density under drought at the mature phase. Drought decreased AM fungal richness in soil and roots at the jointing and mature phases, respectively. AM fungal community composition in soil and roots was significantly different between the jointing phase and the tasseling and mature phases. AM fungal community composition was influenced by fertilization at the tasseling phase in soil, but by irrigation at the jointing and tasseling phases in roots. Our findings highlight the differential response of AM fungi in soil and roots to drought and fertilization during the various phases of maize development in this dryland agroecosystem.

Conservation tillage enhances crop productivity and decreases soil nitrogen losses in a rainfed agroecosystem of the Loess Plateau, China

Conservation tillage has been recommended as one of the effective soil management practices for mitigating the negative environmental effects of synthetic ammonia application and hence achieving cleaner agricultural production. However, information about how long-term conservation tillage affects agroecosystem nitrogen balance in dryland winter wheat-summer maize cropping is limited. Based on a long-term (>9 yr) field tillage experiment and in-situ observation, we assessed the effects of different tillage practices (i.e., chisel plough tillage (CPT), zero tillage (ZT), and conventional ploughing tillage (PT)) on soil nitrogen balance and crop productivity in the 2016–2017 and 2017–2018 growing seasons. Each tillage practice was exposed to a local widely adopted N application rate (240 kg ha−1 yr−1) in both seasons. Our results indicated that, compared with PT, CPT and ZT significantly (P < 0.05) reduced N2O emissions by 39.7% (2.8 kg N ha−1 yr−1) and 55.3% (3.9 kg N ha−1 yr−1), and N leaching by 52.3% (11.8 kg N ha−1 yr −1) and 147.7% (33.3 kg N ha−1 yr−1) across the two growing seasons, respectively. CPT significantly enhanced crop aboveground N uptake by 4.0%, and increased the annual crop yield by 5.9–8.1% (0.8–1.2 t ha−1 yr−1). Although CPT and ZT enhanced NH3 volatilization by 46.7% (14.6 kg N ha−1 yr−1) and 84.3% (26.3 kg N ha−1 yr−1), the total N losses under CPT and ZT were decreased on an average by 7.4% and 22.4%, respectively. Overall, CPT and ZT significantly increased the accumulation of soil total nitrogen in the 0–100 cm layer by 34.8 and 54.1 kg N ha−1 yr−1, respectively. Taking N inputs and outputs together, CPT achieved a lower N surplus mainly due to increased crop N harvest and reduced N losses including gaseous emissions and hydrological leaching. Our findings suggest that long-term chisel plough tillage in dryland agroecosystems could serve as a promising soil management practice in increasing crop productivity and maintaining sustainability through enhancing N removal from crop biomass and decreasing N losses via N2O emission and nitrate-N leaching.

Ammonia volatilization as the major nitrogen loss pathway in dryland agro-ecosystems

The losses of excessive reactive nitrogen (N) from agricultural production pose detrimental impacts on water, air and land. However, N budgets of agroecosystems are still poorly quantified, presenting a barrier to understand the N turnover in agriculture. Agricultural ammonia (NH3) volatilization has been recognized as a crucial contribution to the pollution of fine particulate matters over China through reacting with acid gases. Building on these challenges, the first national-scale model analysis was constructed on the N budgets to gain an overall insight into the current status of N flows in Chinese dryland systems towards sustainable N management. Total inputs of soil N in Chinese dryland soils were estimated at 121 kg N ha−1 in 2010, considering all pathways including N manure, fertilizer, atmospheric deposition and litter from crop residues. Atmospheric N deposition accounted for 25% of N fertilizer plus N manure in Chinese dryland soils, suggesting that N deposition could not be ignored when estimating total N inputs to Chinese dryland soils. The highest ratio of NH3 volatilization to total N outputs was found at 43 kg N ha−1 (∼21%) in Northern China, followed by 41 kg N ha−1 (∼20%) in Sichuan Basin and 25 kg N ha−1 (∼26%) in Northeastern China. The modeling results indicated that, if a 20% decrease in N fertilizer plus N manure was achieved, it would lead to a 24% (7–49%) reduction in NH3 volatilization. Substantial reductions of NH3 volatilization would also be achieved by making an improvement in changing management practices (controlled release fertilizer and full irrigation). The results would give an overall insight into N budgets in Chinese dryland soils. The constructed N budgets assisted with understanding agricultural N flows and NH3 pollution, and evaluated the impacts of human activities on N cycle towards a precise way to regulate agricultural management.

Soil and crop management systems that ameliorate damage caused by decades of dryland agroecosystem mismanagement

AbstractSustainable crop production in the Great Plains of North America has been challenging since early settlement times, and mismanagement has severely damaged our dryland agroecosystems. The unintentional damage stemmed from using practices unsuited to dryer climates. In fact, the management practices imported from more humid agricultural areas during the settlement period were considered the best ways to farm. The Dust Bowl era was the disastrous result of creating bare soil surfaces, with aggregates pulverized by excessive tillage on millions of hectares of land. It became obvious to pioneer scientists that retaining cover on the soil surface was critical to sustainability and their early efforts resulted in a widely adopted practice known as stubble mulch. Stubble mulch practices markedly decreased the rate of damage to dryland ecosystems. Advent of herbicidal weed control led to reduced and no‐till practices that not only increased soil cover, but also significantly enhanced soil water conservation. This paper focuses on how and why the coupling of conservation tillage and cropping intensification is ameliorating the damage that accrued over decades of agroecosystem mismanagement. The objectives of this paper are to (a) remind us of fragile nature of the Great Plains ecosystem, (b) review how and why ecosystems were degraded, and (c) identify principles and associated practices for amelioration.

The Assessment of Technology Millet (Setaria Italica (L) Beauv.) Based Multiple Cropping on Dry Land in Moluccas

Millet (Setaria italica (L) Beauv.) is classified as a cereal plant, potentially developed as an alternative food ingredient to support food self-sufficiency in the region and nationally. The study was carried in Waeperang, Lilialy Subdistrict, Buru Regency in 2017 with the aim of obtaining recommendation for technology package for millet-based double cropping that was able to increase productivity &gt; 20%. The study was carried out with an adaptive approach, field trial approach, and dry land agroecosystem approach, using Randomized Block Design with four treatments and repeated five times (farmers as replications). Four treatments were tested, namely: (1) Technology of Existing Planting Pattern (Millet - Peanuts - Fallow), (2) Technology of Improved Farmer Planting Pattern (Millet + Corn - Peanuts - Fallow), (3) Technology of Introducing I Planting Pattern (Millet + Corn - Peanuts - Mungbeans) and (4) Technology of Introducing II Planting Pattern (Millet + Corn/Cassava - Peanuts - Mungbeans). The results of the study indicated that the multiple cropping pattern based on millet can increase productivity of millet compared to monoculture. Intercropping of millet, namely Introduction I Planting Pattern (C Pattern): Millet + Corn - Peanuts - Mungbeans and Introduction II Planting Pattern (D Pattern): Millet + Corn/Cassava - Peanuts - Mungbeans can increase the productivity of millet crops are 23.04% and 51.55%, respectively. Introduction D Pattern (Millet + Corn/Cassava - Peanuts - Mungbeans) can be recommended as a double cropping pattern on dry land in Moluccas, and support dimensions of a food security, i.e access, availability, utilization and stability of food.

Combined application of biochar and farmyard manure reduces wheat crop eco-physiological performance in a tropical dryland agro-ecosystem

Combined application of biochar and organic fertilizer has been widely recommended for improving soil bio-physical properties. However, detailed exploration of combined application on crop eco-physiological performance is limited. In this study, we explored the agronomic and eco-physiological responses of wheat crop grown under different combinations of rice-husk ash (RHA/biochar), farmyard manure (FYM) and chemical fertilizers in a silty loam soil. Aboveground biomass varied significantly across the treatments and was found higher (11–31%) under chemical fertilizer-applied treatments, but lower (6%) under sole RHA-applied treatment as compared to control. Crop eco-physiological parameters varied significantly (at P < 0.01) with the treatment and crop growth stages. Sole chemical fertilizer- and FYM-applied treatments showed better (5–26% higher), whereas sole RHA- and combined RHA + FYM-applied treatments showed poor (2–15% lower) photosynthetic rate as compared to control. Ear length was moderately correlated (r = 0.53) with aboveground biomass and explained 27% of the variability in it. Transpiration rate, intercellular CO2 concentration and water-use efficiency (WUEp) were identified as the major determinants of photosynthetic rate during vegetative and maturity growth stages. WUEp along with transpiration rate was found to explain 94% of the variability in photosynthetic rate for overall dataset. The findings suggest that combined RHA + FYM amendment may limit crop agronomic and eco-physiological performance due to nutrient immobilization. Therefore, combined application of RHA + FYM with chemical fertilizer application at reduced rate can be suggested for improving crop eco-physiological and agronomic responses under the sustainable agriculture practices in silty loam soils of tropical dryland agro-ecosystems.

Performance of several varieties of maize and upland rice in the intercropping system in Northern Gorontalo

This study aims to: 1) knowing the performance of several varieties of maize and upland rice on the application of monoculture and intercropping system cultivation technology, and 2) Financially analyzing maize and upland rice farming with monoculture and intercropping systems in dry land agroecosystems in Gorontalo Province. This assessment activity was carried out with a participatory approach involving 15 cooperative farmers on 12 ha of land in Durian Village, Gentuma Raya District, North Gorontalo Regency on dry climate dry land agroecosystem with a wavy topography in 2018. Maize varieties planted were Nasa 29, Bima 2, Bima 20, HJ 21, JH 27, Bisi 18, NK 22, and Pioneer 35. The varieties of upland rice planted were Situ Bagendit, Inpago 8, Inpago 11, Inpari 42, Ponelo, and Towuti. The results of the study showed that the average productivity of maize with a monoculture system (5.13 t / ha) was higher than the average productivity of maize with an intercropping system (3.61 t / ha). In the monoculture system, maize varieties with the highest productivity was JH 27 (6.4 t / ha). In the intercropping system, maize varieties of the Indonesian Agency for Agricultural Research and Development (IAARD) of BIMA 2 achieved the highest productivity at 4.83 t / ha. The average productivity of upland rice with a monoculture system (4.46 t / ha) was higher than the average productivity of upland rice with an intercropping system (2.17 t / ha). In the monoculture system, the highest productivity was Inpago 11 variety (5.67 t / ha). Whereas in the intercropping system, the highest productivity was the Ponelo variety (3.95 t / ha). Based on farming financial analysis, efficient farming systems were successively from highest to low, namely upland rice monoculture, maize intercropping systems with upland rice, and maize monoculture.

Optimizing multifunctional agroecosystems in irrigated dryland agriculture to restore soil carbon – Experiments and modelling

Irrigated dryland agroecosystems could become more sustainable if crop and soil management enhanced soil organic carbon (SOC). We hypothesized that combining high inputs from cover crops with no-tillage will increase long-term SOC stocks. Caatinga shrublands had been cleared in 1972 for arable crops and palm plantations before implementing field experiments on Mango and Melon systems (established in 2009 and 2012, respectively). Each of the two experiments were managed with no-till (NT) or conventional till (CT), and three types of cover cropping, either a plant mixture of 75% (PM1) or 25% (PM2) legumes, or spontaneous vegetation (SV). The RothC model was used with a daily timestep to simulate the soil moisture dynamics and C turnover for this dry climate. Carbon inputs were between 2.62 and 5.82 Mg C ha−1 year−1 and increased the depleted SOC stocks by 0.08 to 0.56 Mg C ha−1 year−1. Scenarios of continuous biomass inputs of ca. 5 Mg C ha−1 year−1 for 60 years are likely to increase SOC stocks in the mango NT beyond the original Caatinga SOC by between 19.2 and 20.5 Mg C ha−1. Under CT similar inputs would increase SOC stocks only marginally above depletion (2.75 to 2.47 Mg C ha−1). Under melon, annual carbon inputs are slightly greater (up to 5.5 Mg C ha−1 year−1) and SOC stocks would increase on average by another 8% to 22.3 to 20.6 Mg C ha−1 under NT and by 8 Mg C ha−1 under CT. These long-term simulations show that combining NT with high quality cover crops (PM1, PM2) would exceed SOC stocks of the initial Caatinga within 20 and 25 years under irrigated melon and mango cultivation, respectively. These results present a solution to reverse prior loss of SOC by replacing CT dryland agriculture with irrigated NT plus high input cover crops agroecosystems.

Analisis kelayakan ekonomi sistem pertanian terpadu pada zona agroekosistem lahan kering dataran rendah

This study aims to analyze the economic feasibility of integrated farming systems in lowland upland agroecosystem zones. The sampling method used in this study was simple random sampling with a sample of 32 farmers. Data collection techniques used in this study were observation techniques, interview techniques and literature search. Data analysis uses (1) revenue and revenue analysis and (2). Business feasibility analysis (R / C Ratio). The results showed that the results of the economic feasibility analysis of integrated farming systems in lowland dry land agroecosystems in Fatukanutu village, Kupang district, with an average land area of ​​1 ha. The total cost needed is IDR 28,015,000, with total receipts received IDR 76,902,000, and an income of IDR 48,887,000 per planting season. With an R / C Ratio of 2.73.&#x0D;

Performances Holstein Frisien (FH) dairy Cow in different agricultural ecosystem

This research was about the performance Friesian Holland dairy cow in different agricural ecosystems inIndonesia. The objective of research was to study growth performance, body weight and milk production FH in Indonesia. The method of the research was survey method, with the technique of determining farmers proportionally. Sampling farmers and their livestock by random sampling method. The data was processed using SPSS 22.0 for the simple descriptive analysis and then tested statistically used T-Test. The results it was concluded that growth, body weight, and milk yield of dairy cows were influenced by agroecosystems, in the dry land agroecosystems and located on or adjacent to forests (dryland and tropical forest/AES DL-Forest), productivity of dairy cows was better than irrigated and dry land with wide balanced rice agroecosystems (DL-IRF) and rainfed and dry land agroecosystems (AES DL-Rainfed).

Finding a Suitable Niche for Cultivating Cactus Pear (Opuntia ficus-indica) as an Integrated Crop in Resilient Dryland Agroecosystems of India

Climate change poses a significant threat to agroecosystems, especially in the dry areas, characterized by abrupt precipitation pattern and frequent drought events. Ideal crops, tolerant to these events, such as cactus, can perform well under such changing climatic conditions. This study spatially maps land suitability for cactus (Opuntia ficus-indica) cultivation in India using the analytical hierarchical process (AHP). Nine essential growth factors that include the climate and edaphic components were considered for the period 2000 to 2007. About 32% of the total geographic area of the country is in the high to moderate suitable category. Remaining 46% falls under the marginally suitable and 22% under the low to very low suitable category. The suitability analysis, based on the precipitation anomaly (2008–2017), suggests a high probability of cactus growth in the western and east-central part of India. The relationship with aridity index shows a decreasing rate of suitability with the increase of aridity in the western and east-central provinces (β~−1 to −2). We conclude that integrating cactus into dryland farming systems and rangelands under changing climate can be one plausible solution to build resilient agro-ecosystems that provide food and fodder while enhancing the availability of ecosystem services.

Model of sustainable land management (study at Bukit Sepuluh Ribu area of Bungursari Sub-District, Tasikmalaya City, West Java)

This study is associated with the increased pressure on hill resources due to land conversion that causes environmental degradation and leads to environmental unsustainability. The evenly spread hill known as Bukit Sepuluh Ribu, is a source of community life. The hill formed by the eruption of a volcano, has a land cover, namely close to forest vegetation. The study location is in Bukit Sepuluh Ribu area that has ecological, hydrological, geological and aesthetic environmental function. The concept of community empowerment through Agro-ecosystem can be a solution, thus the utilization of the hill is economically profitable and environmentally sustainable. There are land use unsuitability referring to the existing spatial plan (682.9 Ha), namely high densely settlement area (264.67 Ha), other agriculture (359.21 Ha) and mining areas (58.51 Ha), Through the concept of appropriate community empowerment in accordance with the rules and typology of hill areas can provide the potential benefits of ecosystems and produce products of economic value without damaging them. The concept of empowerment through dryland agro-ecosystem by combining forest-based agriculture activities is one of the solutions to the problem of land management.

Impacts of Agricultural Management Systems on Biodiversity and Ecosystem Services in Highly Simplified Dryland Landscapes

Covering about 40% of Earth’s land surface and sustaining at least 38% of global population, drylands are key crop and animal production regions with high economic and social values. However, land use changes associated with industrialized agricultural managements are threatening the sustainability of these systems. While previous studies assessing the impacts of agricultural management systems on biodiversity and their services focused on more diversified mesic landscapes, there is a dearth of such research in highly simplified dryland agroecosystems. In this paper, we 1) summarize previous research on the effects of farm management systems and agricultural expansion on biodiversity and biodiversity-based ecosystem services, 2) present four case studies assessing the impacts of management systems on biodiversity and ecosystem services across highly simplified dryland landscapes of the Northern Great Plains (NGP), USA, 3) discuss approaches to sustain biodiversity-based ecosystem services in drylands, and 4) present a conceptual framework for enhancing agricultural sustainability in the drylands through research, policy, economic valuation, and adaptive management. An analysis of the land use changes due to agricultural expansion within the Golden Triangle, a representative agricultural area in the NGP, indicated that the proportion of land conversion to agriculture area was 84%, 8%, and 7% from grassland, riparian, and shrubland habitats, respectively. Our results showed this simplification was associated with a potential reduction of pollination services. Also, our economic analysis projected that if 30% parasitism could be achieved through better management systems, the estimated potential economic returns to pest regulation services through parasitoids in Montana, USA alone could reach about $11.23 million. Overall, while dryland agroecosystems showed a significant loss of native biodiversity and its services, greater pest incidence, and a decrease in plant pollinator networks, these trends were moderately reversed in organically managed farming systems. In conclusion, although land use changes due to agricultural expansion and industrialized farming threaten the sustainability of dryland agroecosystems, this impact can be partially offset by coupling ecologically-based farming practices with adaptive management strategies.

Improving dryland cropping system nitrogen balance with no‐tillage and nitrogen fertilization

AbstractStudies on N balance due to N inputs and outputs and soil N retention to measure cropping system performance and environmental sustainability are limited due to the complexity of measurements of some parameters. We measured N balance based on N inputs and outputs and soil N retention under dryland agroecosystem affected by cropping system and N fertilization from 2006 to 2011 in the northern Great Plains, USA. Cropping systems were conventional tillage barley (Hordeum vulgaris L.)–fallow (CTB‐F), no‐tillage barley–fallow (NTB‐F), no‐tillage barley–pea (Pisum sativum L.) (NTB‐P), and no‐tillage continuous barley (NTCB). In these cropping systems, N was applied to barley at four rates (0, 40, 80, and 120 kg N ha−1), but not to pea and fallow. Total N input due to N fertilization, pea N fixation, soil N mineralization, atmospheric N deposition, nonsymbiotic N fixation, and crop seed N and total N output due to grain N removal, denitrification, volatilization, N leaching, gaseous N (NOx) emissions, surface runoff, and plant senescence were 28–37% greater with NTB‐P and NTCB than CTB‐F and NTB‐F. Total N input and output also increased with increased N rate. Nitrogen accumulation rate at the 0–120 cm soil depth ranged from –32 kg N ha−1 y−1 for CTB‐F to 40 kg N ha−1 y−1 for NTB‐P and from –22 kg N ha−1 y−1 for N rates of 0 kg N ha−1 to 45 kg N ha−1 y−1 for 120 kg N ha−1. Nitrogen balance ranged from 1 kg N ha−1 y−1 for NTB‐P to 74 kg N ha−1 y−1 for CTB‐F. Because of increased grain N removal but reduced N loss to the environment and N fertilizer requirement as well as efficient N cycling, NTB‐P with 40 kg N ha−1 may enhance agronomic performance and environmental sustainability while reducing N inputs compared to other management practices.

Characterizing the Enduring Nature of Dryland Agro-ecosystems: Irrigated and Rain-fed Land Uses in Chamo Sub Basin, Southern Ethiopia

Characterizing soils, land use and providing suggestion for sustainable utilization of land resources in the Ethiopian Rift valley flat plain areas of Lake Chamo Sub-Basin is essential. The objectives of this study were, therefore, to characterize land use constraints and to assess the status of organic matter, macro and micro-nutrients and soil salinity for planning appropriate land management. A systematic soil survey and field observations weremade to gather information on land uses. Physiognomic vegetation classification was done in accordance with the FAO classification system, i.e. annual croppings, perennial croppings, grazing land and natural forest. A total of 120 soil samples were randomly collected from different land uses, which were prepared into 12 composites and analyzed in Ethiopia Water Works Design and Supervision Enterprise Laboratory. Organic matter, nitrogen, base saturation, exchangeable (potassium, calcium and magnesium), and phosphorus contents were low in cultivated soils compared to natural forest. Soil salinity was observed in irrigated banana and cotton field soils compared to rain-fed agriculture. Clay, nitrogen, phosphorus and potassium contents were positively correlated with organic matter and electrical conductivity. Also soluble cations and anions were varied along different land uses. Also, organic matter, exchangeable (sodium, calcium), cation exchange capacity, phosphorus and micronutrient contentswere positively correlated with soluble salts and electrical conductivity.

Conservation Systems for Positive Net Ecosystem Carbon Balance in Semiarid Drylands

Core Ideas The soil organic C dynamics and net ecosystem C balance of five dryland cropping systems were compared. Conservation systems stored up to 15% more soil organic C than conventional system. Net ecosystem C balance was positive with cover cropping. Cover crops and conservation tillage are crucial for soil C storage in drylands. Biomass C inputs often limit agroecosystem C dynamics, nutrient cycling, and soil organic carbon (SOC) storage in semiarid drylands. This study evaluated SOC and net ecosystem carbon balance (NECB) of five cropping systems in the drylands of the Southern Great Plains. Cropping systems evaluated included corn (Zea mays)–sorghum [Sorghum bicolor (L.) Moench] rotation with conventional tillage without cover cropping (CTNC), strip tillage with and without cover cropping (STCC and STNC, respectively), and no tillage with and without cover cropping (NTCC and NTNC, respectively). After 4 yr of experimental tillage, we measured CO2 emissions, soil and soil surface air temperatures, soil moisture content, potentially mineralizable carbon (PMC), total SOC, total nitrogen (TN), and net primary productivity (NPP). Conservation systems (any treatments including no‐till, strip till, or cover crops) had 5 to 6°C lower soil temperature and 2.8 to 4.9°C lower soil surface air temperature and stored 2.3 to 3.9% more soil moisture content than CTNC. Conservation systems also stored 15.2% more SOC than CTNC. Cropping systems that integrated cover crops in the rotation (STCC and NTCC) had greater NPP and positive NECB. Regardless of tillage management, cover cropping had a greater NECB, including SOC (NECBSOC) than CTNC. Reducing tillage and diversifying cropping systems through cover cropping can benefit semiarid dryland agroecosystems by increasing SOC storage and maintaining positive NECB.

Hierarchical responses of soil organic and inorganic carbon dynamics to soil acidification in a dryland agroecosystem, China

Soil acidification is a major global issue of sustainable development for ecosystems. The increasing soil acidity induced by excessive nitrogen (N) fertilization in farmlands has profoundly impacted the soil carbon dynamics. However, the way in which changes in soil pH regulating the soil carbon dynamics in a deep soil profile is still not well elucidated. In this study, through a 12-year field N fertilization experiment with three N fertilizer treatments (0, 120, and 240 kg N/(hm2•a)) in a dryland agroecosystem of China, we explored the soil pH changes over a soil profile up to a depth of 200 cm and determined the responses of soil organic carbon (SOC) and soil inorganic carbon (SIC) to the changed soil pH. Using a generalized additive model, we identified the soil depth intervals with the most powerful statistical relationships between changes in soil pH and soil carbon dynamics. Hierarchical responses of SOC and SIC dynamics to soil acidification were found. The results indicate that the changes in soil pH explained the SOC dynamics well by using a non-linear relationship at the soil depth of 0–80 cm (P=0.006), whereas the changes in soil pH were significantly linearly correlated with SIC dynamics at the 100–180 cm soil depth (P=0.015). After a long-term N fertilization in the experimental field, the soil pH value decreased in all three N fertilizer treatments. Furthermore, the declines in soil pH in the deep soil layer (100–200 cm) were significantly greater (P=0.035) than those in the upper soil layer (0–80 cm). These results indicate that soil acidification in the upper soil layer can transfer excess protons to the deep soil layer, and subsequently, the structural heterogeneous responses of SOC and SIC to soil acidification were identified because of different buffer capacities for the SOC and SIC. To better estimate the effects of soil acidification on soil carbon dynamics, we suggest that future investigations for soil acidification should be extended to a deeper soil depth, e.g., 200 cm.

Comparing empirical and survey-based yield forecasts in a dryland agro-ecosystem

Accurate crop yield forecasts before harvest are crucial for providing early warning of agricultural losses, so that policy-makers can take steps to minimize hunger risk. Within-season surveys of farmers’ end-of-season harvest expectations are one important method governments use to develop yield forecasts. Survey-based methods have two potential limitations whose effects are poorly understood. First, survey-based forecasts may be subject to errors and biases in the response data. For example, the weather variables that most impact yields may not be the same as those that farmers consider when shaping their yield expectations, thereby undermining forecast accuracy. Secondly, surveys are typically conducted late in the growing season, giving the government less advance notices of potential crop failures or low yields, and are costly to implement. Here we investigate these limitations within the context of Zambia’s annual Crop Forecast Survey (CFS). Concerning the first limitation, we analyzed the differences between CFS-predicted yields and reported yields collected by Post Harvest Surveys, and found that excess rainfall during the planting stage was more important to the actual yield than to farmers’ yield forecasts. For the second limitation, we evaluated whether a simple empirical yield forecast model could produce earlier and more accurate yield forecasts than the CFS. A random forest model using weather variables, soil texture, and soil pH as predictors were able to produce yield forecasts at the same or higher accuracy since the planting season.