June Harvest Research Articles

Application of a Multi-Spectral UAV Imagery in Germplasm Characterization: Prediction of Forage Biomass and Growth Patterns of Cicer Milkvetch (Astragalus cicer L.) Populations

Unmanned aerial vehicles (UAV)-based multi-spectral imaging could reduce the intensive labour required in phenotyping germplasm in crop breeding. The objectives of this study were to examine if UAV-based imaging could differentiate cicer milkvetch (Astragalus cicer L.) germplasm and identify UAV-based vegetation indices with correlations to its dry matter yield (DMY). A spaced nursery from 27 cicer milkvetch populations was established near Saskatoon, SK, Canada, in 2019. From 1 June to 15 October in 2020 and 2021, phenotypic traits including maximum stem length, leaf number per stem, rhizome spread rate, and stem density, along with two UAV-measured traits, green area and canopy volume, were measured bi-weekly. Forage DMY was determined in late June and mid-October of each year. In this study, normalized difference vegetation index (NDVI) green area and NDVI canopy volume data differentiated the three selected populations. NDVI green area had the highest correlation with forage DMY among the traits (June harvest: r = 0.91, October harvest: r = 0.77). Among measured phenotypic traits, maximum stem length had the highest correlation with forage DMY (June harvest: r = 0.74, October harvest: r = 0.83), which was significantly correlated to NDVI green area. The results indicated potential use of UAV-phenotyping in single plant evaluation in plant breeding.

Analisis Pendapatan Usahatani Kacang Merah Berdasarkan Status Kepemilikan Lahan Di Desa Tempok Kecamatan Tompaso Kabupaten Minahasa

The aim of the research is to analyze red bean farming income based on land ownership status in Tempok Village, Tompaso District, Minahasa Regency. The research took place from June to August 2023. The data used in the research were primary data obtained from direct interviews with red bean farmers using questionnaires, and secondary data obtained from research results and journals. Sampling used a purposive sampling method, namely farmers were selected based on the last harvest in May and June, and the samples were divided into three categories, namely farmers who own their own land, farmers who rent land, and sharecroppers who work on other people's land. The number of respondents was 12 red bean farmers consisting of 4 owner farmers, 4 tenant farmers and 4 sharecroppers. The data collected was analyzed descriptively using farming income analysis. The results of the research show that red bean farming income is based on land ownership status, namely: owner farmers amounting to IDR49.129.667, tenant farmers amounting to IDR41.991.500, and sharecroppers amounting to IDR25.925.000 per planting season.

Benefits of a robotic chamber system for determining evapotranspiration in an erosion-affected, heterogeneous cropland

Abstract. In the light of the ongoing global climate crisis and the related increases in extreme hydrological events, it is crucial to assess ecosystem resilience and – in agricultural systems – to ensure sustainable management and food security. For this purpose, a comprehensive understanding of ecosystem water cycle budgets and spatiotemporal dynamics is indispensable. Evapotranspiration (ET) plays a pivotal role in returning up to 90 % of incoming precipitation back to the atmosphere. Here, we studied the impacts of soil types and management on an agroecosystem's seasonal cumulative ET (ETsum) and agronomic water use efficiency (WUEagro, the dry matter per unit of water used by the crop). To do so, a plot experiment with winter rye (17 September 2020 to 30 June 2021) was conducted in an eroded cropland which is located in the hilly and dry ground moraine landscape of the Uckermark region in northeastern Germany. Along the experimental plot (110 m × 16 m), two closed chambers were mounted on a robotic gantry crane system (FluxCrane as part of the AgroFlux platform) and used to determine ET. Three soil types representing the full soil erosion gradient related to the hummocky ground moraine landscape (extremely eroded: Calcaric Regosol; strongly eroded: Nudiargic Luvisol; non-eroded: Calcic Luvisol) and additional topsoil dilution (topsoil removal and subsoil admixture) were investigated (randomized block design, three replicates per treatment). Five different modeling approaches were used and compared in the light of their potential for reliable ETsum over the entire crop cultivation period and to reproduce short-term (e.g., diurnal) water flux dynamics. While machine-learning approaches such as support vector machines (SVMs) and artificial neural networks (with Bayesian regularization; ANN_BR) generally performed well during calibration, SVMs also provided a satisfactory prediction of measured ET during validation (k-fold cross-validation, k=5). We found significant differences in dry biomass (DM) and small trends in ETsum between soil types, resulting in different WUEagro. The extremely eroded Calcaric Regosol showed an up to 46 % lower ETsum and up to 54 % lower WUEagro compared to the non-eroded Calcic Luvisol. The key period contributing to 70 % of ETsum spanned the beginning of stem elongation in April to the harvest in June. However, differences in the ETsum between soil types and topsoil dilution resulted predominantly from small differences between the treatments throughout the cultivation rather than only during this short period of time.

Blue-stain development on Norway spruce logs under alpine conditions

Discoloration of the sapwood caused by blue-stain fungi on conifer logs during interim storage causes significant loss to the forest industry. The fungal infection is often associated with bark beetle attacks because the spores are transmitted by the beetles. They can also be disseminated by rain-splash and moist air. While there are methods to protect logs from sap-stain in wood yards, this is often not possible in the forest for practical and regulatory reasons. Timing of harvesting and timely transportation are often the only ways to prevent blue-stain. To estimate the urgency of transportation, knowledge of the growth of blue-stain fungi and its dependence on weather conditions is of great interest. The proportion of discolored sapwood on Norway spruce logs was recorded along a time series, together with weather data in two field experiments conducted in spring and summer at two alpine sites in Austria. A predictive model was developed to estimate the proportion of blue-stained sapwood based on the temperature sum to which the logs were exposed. After harvest in March, there was a time lag of 82 and 97 days at the two respective sites, caused by initially low temperatures, before discoloration started. In contrast, sap-stain occurred 14 days after the harvest in June, when warm conditions prevailed from the start. The nonlinear least square regression model can help to estimate a window of opportunity to transport wood before it loses its value and serves as a sub model for lead time estimation within logistic decision support systems.

Erosion Dynamics of Cultivated Kelp, Saccharina latissima, and Implications for Environmental Management and Carbon Sequestration

A growing trend of interest for the cultivation of kelp is driven by predictions for high global demands of important commodities, which require the development of alternative supplies of natural resources. In this study the dynamics of loss of biomass from cultivated Saccharina latissima were studied from February to August 2018 at two kelp farms in Northern (69°45.26′N/019°02.18′E) and in Mid-Norway (63°42.28′N/08°52.23′E). Kelp fronds at each farm were individually followed throughout the growing season. Sectional regression was applied for conversion of measured frond lengths to estimated dry weights. The study shows that between 40 and 100% of all individuals in the studied kelp population constantly eroded slightly from their distal ends. However, until June the accumulated loss was only 8% of produced dry weight. Due to dislodgement of whole sporophytes this picture changed in July and August to heavy losses in Mid-Norway. Thus, the overall losses of kelp in terms of accumulated dry weight were only 8–13% of the gross growth until harvest in June in Mid-Norway and August in Northern Norway. Losses increased significantly in Mid-Norway during July and reached 49.4% of the annual production in August. The rates of losses were separated into specific erosion and dislodgement rates. Erosion rates over the whole experimental period for the two sites were not significantly different, while differences in dislodgement rates between farm sites proved to be highly significant. The exported annual amount of carbon was estimated on the basis of lost and measured carbon content in the tissue. From these data a scenario was built for a commercial Norwegian kelp farm growing S. latissima showing a carbon export of 63–88 g C m–2y–1. This is eight times less than has been reported from scenarios for kelp farms in China. This study confirms that optimal timing of harvest is the most important management tool for avoidance of heavy losses from kelp farms. In conclusion, an industry with early harvest will likely have a low carbon export, while a late-harvested bulk production could export four to six times as much carbon with an increased potential for carbon sequestration.

Integrating Straw Management and Seeding to Improve Seed Yield and Reduce Environmental Impacts in Soybean Production

Multiple cropping systems boost grain yields and have an immense potential to increase land productivity. In such cropping systems in China, soybean is directly seeded after the wheat harvest in early June. After the wheat harvest, the farmland has low amounts of soil moisture and contains large amounts of wheat straw, which negatively affect soybean growth and yields. To address these challenges, an integrated management practice (IMP) than can achieve precise direct seeding and straw mulching return, was developed. In this study, differences in the soil temperature and moisture, seedling quality, dry matter accumulation, soybean yield, and greenhouse gas emissions were investigated between IMP and the farmers’ practices (FP). Compared with the FP treatment, IMP significantly increased the soil moisture and decreased the soil temperature in the topsoil layer. In addition, under the IMP treatment, the rate of emergence and developmental uniformity of soybean plants significantly increased by 21.7% and 99.5%, respectively, thus increasing the leaf area index by 30.0% and dry matter accumulation by 12.0% and, in turn, increasing soybean yields by 24.7%. A principal component analysis showed that the dry matter weight, relative water content, leaf area index, and developmental uniformity were strong sensitivity indices for the IMP treatment. In addition, the intensity of emission of N2O and greenhouse gases under IMP both decreased significantly by 25.1% and 28.9% compared with the FP, respectively. Thus, it was concluded that IMP is a suitable farming practice for sustainable agricultural production, and it has broad prospects for application in wheat–soybean double cropping systems in China and other similar areas globally.

Temperature Limits for the Brown Wheat Mite, in Colorado.

Brown wheat mites, Petrobia latens (Müller 1776, Acari: Tetranychidae), are sporadic yet economically damaging pests of winter cereals. In Colorado, their life history is closely tied to the development of winter wheat, where they are present in the field from crop planting in late September through harvest in early June. In order to withstand winter months, these mites are able to survive cold temperatures. However, the mechanisms of cold hardening and their temperature limits are unknown. This research documents the seasonal supercooling points of the brown wheat mite. Their seasonal average supercooling point stayed consistent throughout the year, never varying more than a degree from the overall average supercooling point of -17°C. The greatest variation in supercooling point was seen in the spring, during which supercooling point temperatures ranged from -9.2 to -25.5°C. We also documented the upper and lower lethal temperatures for the brown wheat mite. When comparing small nymphs to large nymph and adult stages, small nymphs were slightly more cold tolerant (lethal temperature estimates required to kill 99% of the population [LT99] were -30.8 and -30.6°C, respectively), but less heat tolerant (LT99 was 50 and 56°C, respectively).

Comparison of transcriptional expression patterns of phenols and carotenoids in 'Kyoho' grapes under a two-crop-a-year cultivation system.

To fully utilize the characteristic climatic conditions in the southern region of China, a two-crop-a-year cultivation system technique for ‘Kyoho’ grape was developed during the past decade. After summer harvest in June, appropriate pruning and chemical treatments promote flowering and fruiting, which enables a second harvest in late December. Due to climatic differences between the two crop growing seasons, grape phenol and carotenoid metabolism differ greatly. The reported study analyzed the transcriptome of the carotenoid and phenylpropanoid/flavonoid pathways in grapes at four different stages during the two growing seasons. Compared with those in summer grapes, expression levels of the majority of genes involved in the carotenoid metabolic pathway in winter grapes were generally upregulated. This result was associated with lower rainfall and much more abundant sunlight during the second growing season. On the other hand, summer cropping strongly triggered the expression of upstream genes in the phenylpropanoid/flavonoid pathway at E-L 33 and E-L 35. Transcript levels of flavonoid 3’,5’-hydroxylase (F3’5’H), flavonoid 3’-hydroxylase (F3’H), flavonoid 3-hydroxylase (F3H) and glutathione S-transferase (GST) were upregulated in winter grapes at the mature stage. Together, these results might indicate that more flavonoids would be synthesized in ripe winter grapes during the mature stage of the second crop under much drier conditions, longer sunlight hours and lower temperature. These data provide a theoretical foundation for the secondary metabolism of berries grown under two-crop-a-year cultivation systems.

Seasonal and depth variations in the chemical composition of cultivated Saccharina latissima

Sugar kelp (Saccharina latissima) is an abundantly available macroalgae species along the Norwegian coast, and there is currently emerging an industry based on seaweed cultivation. In this study, the biomass growth of cultivated S. latissima deployed in February was studied at cultivation depths of 3 and 8 meters (m) and monitored over the period of May, June, and August. The highest biomass production was observed in June at the depth of 3 m (38.3 kg wet weight m−2). Furthermore, all seaweed samples underwent a detailed chemical characterization including analysis of carbohydrates (glucose, mannitol, fucose, xylose, uronic acids), amino acids and minerals. The macroalgae deployed in February at 3 m depth and sampled in June had the highest proportion of total sugars (534.5 g kg−1 of DM) and the lowest content of ash (252.7 g kg−1 of DM). Thus, cultivation at 3 m and harvesting in June are suitable when the feedstock is used for biochemical production of fuels and chemicals. Macroalgae deployed at 8 m depth and harvested in August had the highest proportion of total amino acids (242.4 g kg−1 DM) and ash content (411.5 g kg−1 DM). This biomass may be suitable as a nitrogen and mineral source in microbial growth media. Overall, the choice of cultivation depth and harvesting time depends on the intended use of the seaweed biomass.

The role of poorly crystalline iron oxides in the stability of soil aggregate-associated organic carbon in a rice–wheat cropping system

The stability of the soil organic carbon (SOC) in a rice–wheat rotation paddy soil has been of interest because of the global emission of greenhouse gases from the soil and the sequestration of atmospheric carbon dioxide in the soil, as well as in terms of soil fertility in subtropical Asia. The purpose of this study was to explore the relationship between poorly crystalline iron oxides (Feo) and SOC in bulk soil and soil aggregates. Soil samples were collected after a wheat harvest in June 2014 and after a rice harvest in October 2014 and were separated into large macroaggregates, small macroaggregates, microaggregates, and silt and clay by wet-sieving. The long-term (5-year) application of pig manure compost plus chemical fertilizer (NPKM) increased the SOC content more efficiently than other treatments. The specific carbon mineralization rate (SCMR, rate per unit SOC) increased in the following order: microaggregate<macroaggregate<silt and clay, suggesting that SOC in the microaggregates is more stable than in the silt and clay fraction. The Feo concentration was significantly positively correlated with the SOC content in the bulk soil (P<0.001) and the soil aggregates (P<0.001), but negatively correlated with the SCMR (P<0.001). Compared with chemical fertilization alone (NPK), NPKM not only significantly improved soil aggregation but also efficiently activated the iron oxides as indicated by an increase in the aggregate mean-weight diameter (MWD) and the Feo content. Therefore, we suggested that the seasonal variation of wetting and drying drives the redox transformation of iron oxides and the mobility of Feo, and then affects the distribution of Feo in soil aggregates, which may endow paddy soil with a physico-chemical protection of SOC while application of organic fertilizers enhances this protection.

Is early grass harvest for silage an overlooked reason for skylark Alauda arvensis population decline in Sweden?

In 2015 we studied the relative importance of silage and cereal crops as breeding habitat for the skylark Alauda arvensis. In 2014 we had found that skylarks failed to breed successfully in grass silage fields. We compared skylark density between crops in one organic and one conventional farm, c. 100 ha each, at Kvismaren valley in south Sweden (approx. 59.2°N; 15.4°E). The densities were similar in all crops: 83 territories/km2 in silage and 75 (spring sown) or 80 (autumn sown) in cereal. However, silage harvest in early June and July destroyed, as in the previous year, almost all nests, effectively preventing skylarks from reproducing successfully in that habitat. Cereal fields are not harvested until after the young are fledged. Approximately 45% of the farmland area in Sweden is grass for silage, normally harvested in late May or early June. We suggest that this early harvest is an important and overlooked driver for population decline of birds nesting in such fields.

Efectos de la densidad de siembra, la altura de corte y el mes de cosecha sobre el rendimiento de materia seca y contenido de proteína de Ubon Stylo

En la primera fase de esta investigación y en la presente segunda fase se usaron cuatro niveles de semilla al establecer Ubon Stylo (Stylosanthes guianensis var. vulgaris x var. pauciflora); esta misma variable así como tres alturas de corte y cuatro meses de cosecha a intervalos de 90 d se evaluaron en sus efectos sobre el rendimiento de materia seca (RMS) y contenido de proteína bruta (PB) del forraje. Los niveles de semilla (5, 10, 15 y 20 kg/ha) constituyeron las parcelas principales; las alturas de corte (10, 15 y 20 cm) fueron las subparcelas; y los meses de cosecha (marzo, junio, septiembre y diciembre) las sub-subparcelas. El análisis estadístico reveló que el RMS no se afectó significativamente por la altura de corte ni por las interacciones de esta variable con las otras dos en cuestión. El mes de cosecha si ejerció un efecto (P&lt;0.05) sobre el RMS, y la densidad de siembra mostró una tendencia similar (P&lt;0.063). Además, se detectó una interacción (P&lt;0.05) entre estas dos variables. Las medias de RMS, expresadas en equivalencia anual (kg/ha), correspondientes a las cuatro cosechas consecutivas desde marzo hasta diciembre fueron: 5,949; 11,285; 8,105; y 6,543, siendo la media general 7,970. Los valores de RMS correspondientes a los cuatro niveles de semilla desde 5 hasta 20 kg/ha fueron: 7,488; 8,343; 8,375; y 7,672 kg/ ha. La interacción de nivel de semilla x cosecha quedó ilustrada por el hecho de que el mayor RMS a la cosecha de junio (13,795 kg/ha) se obtuvo con 15 kg/ha de semilla, mientras los RMS máximos en las otras tres cosechas correspondieron al nivel de semilla de 10 kg/ha. La media general de contenido de PB fue de 13.4% sin efectos principales ni interacciones significativas de las variables bajo estudio. Los resultados confirman la conclusión previa de que el nivel de semilla de 10 kg/ha es óptimo para uso en el establecimiento de Ubon Stylo porque promueve un buen RMS sin incurrir en un gasto mayor innecesario. Además, los altos rendimientos obtenidos en verano sugieren que sería posible acortar el intervalo entre cosechas para mejorar el contenido proteico durante esta época del año.

Výnosy vytrvalých trav v létě a na konci vegetačního období

The paper deals with the yields of Festulolium, Dactylis glomerata, Arrhenatherum elatius and Festulolium-Dactylis glomerata mixture during the growing season and at the end of the growing season. The yields were assessed in the Bohemian-Moravian upland at 560 m a.s.l. A small-plot experiment was established in three repetitions. The assessment was made in three subsequent years. The experiment was annually fertilized with 50 kg . ha−1 N, 30 kg . ha−1 P and 60 kg . ha−1 K. Evaluated were dry matter yields and RYT values (Relative Yield Total) in the mixture of Festulolium and Dactylis glomerata. In summer, the sward was used either for one cut (harvest in early June) or two cuts (harvests in early June and late July). At the end of the growing season, the stand was harvested in October or in November or in December. Yields of the first cut in early June ranged from 5.90 to 9.12 t . ha−1. Yields of the second cut in late July ranged from 1.05 to 4.60 t . ha−1. Statistic difference between the species was significant (P &lt; 0.05) in the respective cuts. Total yields of dry matter in the growing season ranged from 7.51 to 10.05 t . ha−1. Number of cuts and year showed a statistically highly significant influence (P &lt; 0.01) on DM yields. The mixture of Festulolium and Dactylis glomerata exhibited an additive relation (RYT = 1) in the first cut and an antagonistic relation (RYT &lt; 1) in the second cut. At the end of the growing season, the yields ranged from 0.71 to 2.27 t . ha−1. Average yields of one-cut swards (harvested in summer in early June) were at the end of the growing season 2.27 t . ha−1 and average yields of two-cut swards (harvested in summer in early June and late July) were 0.79 t . ha−1. From October to December, the yields were decreasing from 1.78 to 1.32 t . ha−1. Species, number of cuts in summer, harvest date at the end of the growing season and year showed a statistically highly significant influence (P &lt; 0.01) on dry matter yields. In the first two production years, the mixture of Festulolium and Dactylis glomerata exhi­bi­ted an antagonistic relation (RYT &lt; 1) at the end of the growing season. In the third production year, the relation between Festulolium and Dactylis glomerata as expressed by the RYT value could be identified as synergic (RYT &gt; 1).

Wild orchid tuber collection in Iran: a wake-up call for conservation

Wild orchids are traditionally harvested as Salep and used in traditional medicine and ice-cream production in Iran. Recently however, illegal harvest of wild orchids for export appears to have grown. This study aimed to: (1) determine the diversity of harvested wild orchid species and their collection sites in Iran; and (2) study the current harvest status and trade chain and volume to estimate the total orchid plant extraction from natural populations. Field surveys of collectors and market surveys of traders were conducted to establish the diversity of collected species, to identify harvest hotspots, and to document harvesting and trade volumes. Sixteen species and subspecies from 7 genera of Orchidaceae are collected for their tubers. Based on estimates from the 2013 April to June harvest season more than 24.5 tons of fresh tubers were collected from three districts in Golestan province alone. It is estimated that this amount of tuber requires the lethal destructive harvesting of 5.5 –6.1 million orchids, with a market value of 320,000 USD. In the Tehran Bazar Salep trade during May–July 2013 was 1.9 tons of dried tubers, with estimated retail value of 310,000 USD. Current orchid collection practices in Iran, which have soared in recent years due to international demand, do not seem sustainable as all tubers are collected destructively. To preserve orchid populations, in the longterm, establishment of specific Orchid Conservation Areas and introduction of sustainable production practices, could alleviate harvesting pressure. In the midterm, development of a DNA barcoding-based molecular identification system could help to monitor and control illegal trade. In the near term, effective implementation of collection bans in excessively harvested areas and strengthening of current regulations are necessary to avoid the catastrophic effects of harvesting on orchid populations, as has been observed in Turkey.

Regional climate response to land surface changes after harvest in the North China Plain under present and possible future climate conditions

AbstractIn this study, we investigated the impacts of land use alterations from harvesting practices on the regional surface climate over the North China Plain. The surface climate responses after harvest in June in regions where double‐cropping is practiced were evaluated using observations and model simulations with the global climate model HadGEM2‐Atmosphere. Responses were modeled under both present and possible future climate conditions. In the model, double‐cropping was represented using the monthly varying fraction of vegetation. This contributed to an improvement in the model simulation over East Asia. Modeling results showed that the land surface was warmer and drier after harvest, and these simulation results were consistent with observations. The bare soil surface after harvest in June had biophysical impacts on the surface climate that were mediated by decreasing evapotranspiration and latent heat flux effects, which increased surface air temperatures and decreased surface humidity. An increase in shortwave radiation also contributed to the rise in temperatures. Under two Representative Concentration Pathways (RCP) scenarios for possible future climate conditions, land conversion induced additional warming in addition to greenhouse gases induced global warming. The RCP 8.5 and RCP 2.6 scenarios demonstrated a warming of 1.0°C and 1.4°C due to harvesting practices in June, respectively. The response magnitude was affected by the climate conditions in each RCP. Our results suggest that potential impacts of harvest on the local climate need to be considered in future projections of CO2‐induced warming on a regional scale.

Management practices effect on seed features of Italian ryegrass following storage period

Italian ryegrass seed crop was established in 2007 with two sowing densities (D1 = 60 cm row spacing and 5 kg ha-1 seeding rate; D2 = 20 cm row spacing and 20 kg ha-1 seeding rate) and using two spring nitrogen rates (0 and 150 kg N ha-1). Seed germination and thousand seed weight (TSW) of Italian ryegrass was observed in first production year. After harvest in June, seeds were stored under standard storage conditions and sampled 90 days after harvest (DAH), and then 2000 DAH. At 90 DAH, seeds were tested for TSW, as well as germination energy and total germination percentage at incubation temperatures of 10, 15, 20 and 25?C. Ryegrass seeds had the best germination energy 90 DAH at 20?C and maximum total germination at 15?C, which implies that early autumn (September-October) is proper sowing period for freshly harvested seeds of Italian ryegrass. Italian ryegrass seeds could maintain satisfactory germination energy (59.3%) and total germination (77.3%) up to 2000 DAH. High seed quality was obtained and applied treatments did not change seed quality significantly unlike storage period which had considerable influence on seed quality. The data can serve for the determination of a proper storage duration management between harvest and sowing of the tested species under ambient conditions of Serbia.

Soil Insect Diversity and Abundance Following Different Fertilizer Treatments on the Loess Plateau of China

The presence of abundant and diverse communities of macro-arthropods is considered an indicator of sustainability in agroecosystems. This study was designed to investigate the effects of different fertilizer treatments on abundance and diversity of insects of arable loess soil on the Loess Plateau of China. These regimes included a control with no fertilizer addition or manure, treatments with application of mineral fertilizers (N, NK, NP, PK, NPK), treatments with NPK in combination with organic materials such as wheat straw or maize stalk, treatments with two rates of organic manure application; and different crop rotations (Rot.1: winter wheat summer maize; Rot.2: winter wheat summer maize soybean intercropping; and Rot.3: winter wheat or rapeseed summer maize soybean intercropping). Soil macro-arthropods were collected from the plough layer (0-20 cm) and sorted by hand after each harvest in June and October 2001 and 2002. A total of 3 132 individuals were collected, from 7 orders and 55 families, dominated by Formicidae (61.72%) and Staphylinidae (14.24%). The results showed that individuals and groups were significantly influenced by sampling dates, while groups were significantly influenced by the fertilization treatments. Soil insect biodiversity, as determined by the Shannon index, was significantly influenced by fertilization and sampling dates. The abundance of soil insects was positively and significantly correlated with soil moisture content in October 2002. Nitrogen, phosphorus and potassium fertilizers and incorporation of organic materials were favorable factors for abundance and diversity in arable loess soil.

Long-Term Impacts of Organic and Inorganic Fertilizers on Carbon Sequestration in Aggregates of an Entisol in Mediterranean Turkey

Soil management practices significantly impact soil aggregation and carbon (C) dynamics. Organic fertilizer and mycorrhizal inoculation also affect aggregate stability and soil C pool. Thus, this study was designed to assess the effects of inorganic and organic fertilizer treatments (control, chemical fertilizer, animal manure, compost, and compost + mycorrhizal inoculation) on bulk density (ρ b ), C and N concentrations, soil organic C (SOC) pool, C sequestration, total N, aggregate fractions, water-stable aggregates (WSA), and mean weight diameter (MWD) in the long-term field experiment initiated in 1996 on the Mediterranean coast of Turkey. Disturbed and undisturbed soil samples were collected from the 0- to 0.15-m and 0.15- to 0.30-m depths after wheat (Triticum aestivum) harvest in June 2010 to determine the soil physical and chemical characteristics. Soils that received animal manure, compost, and compost + mycorrhizae contained more C (in percent), N (in percent), SOC, and total N concentrations than control. In comparison with control, chemical fertilizers also affected soil C and N concentrations and pools by increasing plant biomass production. The C/N ratio of soil was less than 10 in control and chemical fertilizer treatments but more than 10 in animal manure, compost, and compost + mycorrhizae treatments. Organic fertilizers significantly reduced ρ b and increased porosity (in percent). Total amounts and rate of C and N sequestration increased with application of organic fertilizers. The rate (kg C ha ―1 year ―1 ) of C sequestration in 0- to 0.15-m depth was 7.19 for control, 329.6 for animal manure, and 273.4 for the compost + mycorrhizae treatment. Furthermore, organic fertilizers significantly increased the SOC concentrations in different aggregate size fractions. The C and N concentrations in the 0.25- to 1.0-mm aggregate size were higher than those in the less than 0.25-mm fraction. Concentrations of C and N decreased significantly with the decrease in aggregate size less than 0.25 mm (P < 0.0009). Application of organic fertilizers impacted soil ρ b , WSA, and MWD. Compost + mycorrhizae―treated soil had the highest MWD (3.09 mm), and the control treatment had the least (1.49 mm). Decline in aggregate size decreased WSA in compost and mycorrhizae treatments. The high values of MWD were associated with mycorrhizal inoculation rather than with application of organic fertilizer. Application of organic fertilizers including mycorrhizal inoculation contributed considerably to soil aggregation and soil C sequestration. There was more C concentration in 1- to 2-mm and 0.5- to 1-mm aggregate sizes than in the less than 0.25-mm size range. Additional research is needed to assess the role of mycorrhizae on macroaggregate development and C sequestration under long-term soil and crop management systems.

Nitrogen and phosphorus leaching losses from potatoes with different harvest times and following crops

A 3-year field study (2007–2009) was conducted in separately tile-drained plots on a sandy soil in south-west Sweden to determine nitrogen (N) and phosphorus (P) leaching losses from potatoes to the drainage system. Different types of potatoes were grown and harvested at different times followed by different crops in order to identify the potato type/following crop system with the lowest risk of N and P leaching losses. Accumulated annual amounts of N and P lost to drainage between May (potato planting) and the following April varied between 13 and 72kgNha−1 and 0.04 and 0.24kgPha−1 depending on treatment and year. P leaching losses from this particular soil were low and differences between potato types not distinct, but there were significant differences between years. Abnormally high precipitation in summer 2007 led to significantly higher P leaching losses than in other years. N leaching losses were also higher in 2007, but differences between potato types were found in all years. Despite the high mineral soil nitrogen content (Nmin) after harvest in June, early potatoes (EP) with oilseed radish (oil) as catch crop showed the lowest N leaching losses of all potatoes. Potatoes harvested in August (table potato; TP) and September/October (late potato; LP) followed by triticale (tri) sown in October showed the highest leaching losses. Thus under current climate conditions in Sweden, oilseed radish after EP is a suitable catch crop for N, while triticale sown in October is ineffective in preventing N leaching after potatoes. The late harvest of starch potatoes (SP) did not allow establishment of a following crop. However, SP showed lower N leaching losses than TP+tri and LP+tri due to lower residual Nmin in deeper soil layers, low temperatures after harvest decreasing soil N mineralisation and higher C:N ratio of the potato haulm leading to lower N mineralisation potential. As a mean of all years, N leaching losses during and after EP+oil and SP were similar to those from the reference crop spring barley (SB), whereas TP+tri and LP+tri require countermeasures against N leaching.

Long-Term Phosphorus Application Impacts on Aggregate-Associated Carbon and Nitrogen Sequestration in a Vertisol in the Mediterranean Turkey

Fertilizers are among major contributors to the production of aboveground and belowground biomass. Soil organic carbon (SOC) concentration is an important factor affecting crop productivity in semiarid clayey soils of low fertility. A long-term experiment was established in 1998 on a Vertisol in the Mediterranean coast of Turkey, to assess the effects of four rates of application of inorganic phosphorus (P) fertilizers (0, 50, 100, and 200 kg P2O5 ha−1) on soil bulk density (ρb), carbon (C) and nitrogen (N) concentrations, SOC and N pools, C and N sequestration rate, aggregate fractions, water-stable aggregates, and the mean weight diameter (MWD). Thus, disturbed and undisturbed soil samples were collected from the 0- to 15-cm depth after wheat (Triticum aestivum L.) harvest in June 2010 to analyze soil properties. Increase in the rate of application of P fertilizers significantly increased ρb and reduced porosity (%). The SOC concentration was significantly more in the treatment receiving 200 kg P2O5 ha−1 than in the control. The carbon-nitrogen ratio was less than 10 in control and greater than 10 in high P fertilizer treatments. Total amount and rate of C and N sequestration increased with increase in the rate of application of P fertilizers. The mean rate (kg C ha−1 y−1) of C sequestration was −110.9 for control and 556.9 for the highest rate of P fertilizer. Increase in fertilizer rate also significantly increased the rate (kg N ha−1 y−1) of N sequestration, which was −0.21 for control and 28.9 for the highest rate of P fertilizer treatment. The SOC concentrations differed among aggregate-size fractions, which were greater in 0.5- to 2.0-mm aggregate size than those in the fraction of less than 0.25 mm. Greater SOC concentrations were observed in 1- to 2-mm and 0.5- to 1-mm size fractions than in fractions of less than 0.25 mm. Concentrations of C and N decreased significantly with decrease in aggregate size of less than 0.25 mm. There was a general trend of increase in water-stable aggregates and MWD with increase in application of P fertilizer. The highest MWD (1.81 mm) was observed in the high P rate and lowest (1.36 mm) in the control. Macroaggregates were more enriched in C and N than microaggregates. The mean rate of SOC sequestration with 200 kg P2O5 ha−1 treatment is ∼560 kg C ha−1 y−1. The effects of long-term P fertilizer application on C and N sequestration finding(s) of from this study have not been previously observed.