Crop Stand Research Articles

Intercrops as foraging habitats for bees: Bees do not prefer sole legume crops over legume-cereal mixtures

Enhancing crop diversity is an option to make agriculture more sustainable and biodiversity friendly. Intercropping grain legumes together with cereals leads to higher crop diversity and has a broad range of agronomic and ecological benefits. However, sole crop stands of grain legumes might be richer in floral resources than grain legume-cereal intercrops and thus are probably more useful to mitigate the lack of flower resources in agricultural landscapes, which is a main driver of pollinator decline. Yet, little is known about differences between both cropping systems and different legume genotypes in terms of attractiveness for pollinators and how these differences moderate the pollinators’ foraging behavior and consequences for grain legume yields. In a field trial, we analyzed the abundance of flower visiting insects, the foraging behavior of pollinators and related effects on grain yield per plant across six different faba bean genotypes (Vicia faba L.) grown as sole crops or as intercrops with wheat. As foraging behaviors, we considered legal flower visits (i.e. frontal visits) and illegal flower visits (i.e. nectar robbing through bite holes). We recorded characteristics of V. faba genotypes on crop stand level (V. faba plant height, number of V. faba inflorescences and leaf area index (LAI)). V. faba-wheat intercrops and sole crop stands of V. faba were equally attractive foraging habitats for pollinators, implying that intercrops are as suitable as sole crops to mitigate the lack of floral resources. Yield per V. faba plant was positively affected by bee pollination, with this effect being determined by the number of illegal flower visits, suggesting that this foraging strategy does not adversely affect V. faba yields and even has a positive effect. Intercrops had higher yields per V. faba plant than sole crop stands of V. faba, indicating agronomic advantages of this farming practice. Although V. faba genotypes differed in their plant traits, these differences could not explain shifts in the number of flower visiting insects. However, illegal flower visits increased with a higher number of inflorescences whereas the number of legal flower visits declined. Based on our small-scale experiment, we conclude that the use of V. faba-wheat intercrops brings agronomic benefits while serving as a foraging habitat for pollinators that proved to be as attractive as sole crop stands of V. faba.

Including chicory and selecting white clover varieties as strategies to improve temporal stability of forage yield and quality in white-clover-based temporary grassland

Clover-based crop stands are gaining importance in temporary grasslands for intensive livestock production. However, knowledge of their optimal composition to achieve high temporal stability of forage provision is insufficient, particularly so for long cultivation periods. A five-year field trial was conducted to study the effect of adding a non-leguminous forb to clover-based crop stands and to evaluate the impact of the clover variety on inter- and intra-annual stability of forage yield and quality. At two contrasting sites, we cultivated eight white clover (Trifolium repens) populations in pure stands and in mixtures with perennial ryegrass (Lolium perenne) and/or chicory (Cichorium intybus) under a four-cut system without fertilization and determined the seasonal and annual forage yield and quality. Temporal stability of forage provision differed between crop stand types, with marked differences between years and cropping sites. In the study years with lower than long-term precipitation, adding chicory enhanced temporal stability of forage yield as compared to white clover pure stands or clover-grass mixtures at least at the site with deep soil, and maintained or enhanced that of forage quality as compared to clover-grass mixtures. This was often reversed in the study years with higher than long-term precipitation. The white clover populations only slightly varied in temporal stability of forage provision, and did so independently of the crop stand type. Our findings highlight the potential but also constraints of including a non-leguminous forb in unfertilized mown clover-based crop stands, as well as of decisions on the clover variety, to improve temporal stability of forage provision.

Optimizing Nitrogen Sources and Tillage Practices for Wheat Crop Stand and Phenology

Optimizing Nitrogen Sources and Tillage Practices for Wheat Crop Stand and Phenology

Phenology, Crop Stand and Biomass of Wheat in Response to Farmyard Manure and Soil Amendments

Phenology, Crop Stand and Biomass of Wheat in Response to Farmyard Manure and Soil Amendments

Yield structure components of autumn- and spring-sown pea (Pisum sativum L.)

ABSTRACTClimate change brings increasing attention to winter sowing of traditionally spring sown crops. Crop stand height, soil coverage, grain yield and yield components of six winter pea varieties and one spring pea variety were compared in eastern Austrian growing conditions in 2014 and 2015. Crop stands of winter pea were taller up to the end of May before they declined and crop stands of spring pea were taller from early June on. Winter pea covered the soil at least partly over winter and showed faster soil coverage in spring. At the end of May, just some weeks before harvest, spring pea attained equal soil coverage. Grain yield of winter pea was almost double that of spring pea due to higher pod density whereas spring pea produced more grains pod−1 than four out of six winter pea varieties and a higher thousand grain weight than all winter pea varieties. Consequently, grain density was higher for winter pea while the single pod yield was higher for spring pea. Growing winter peas in Central Europe might be a good strategy for increasing grain legume productivity and thereby European feed protein production.

Capturing Maize Stand Heterogeneity Across Yield-Stability Zones Using Unmanned Aerial Vehicles (UAV).

Despite the new equipment capabilities, uneven crop stands are still common occurrences in crop fields, mainly due to spatial heterogeneity in soil conditions, seedling mortality due to herbivore predation and disease, or human error. Non-uniform plant stands may reduce grain yield in crops like maize. Thus, detecting signs of variability in crop stand density early in the season provides critical information for management decisions and crop yield forecasts. Processing techniques applied on images captured by unmanned aerial vehicles (UAVs) has been used successfully to identify crop rows and estimate stand density and, most recently, to estimate plant-to-plant interval distance. Here, we further test and apply an image processing algorithm on UAV images collected from yield-stability zones in a commercial crop field. Our objective was to implement the algorithm to compare variation of plant-spacing intervals to test whether yield differences within these zones are related to differences in crop stand characteristics. Our analysis indicates that the algorithm can be reliably used to estimate plant counts (precision >95% and recall >97%) and plant distance interval (R2 ~0.9 and relative error <10%). Analysis of the collected data indicated that plant spacing variability differences were small among plots with large yield differences, suggesting that it was not a major cause of yield variability across zones with distinct yield history. This analysis provides an example of how plant-detection algorithms can be applied to improve the understanding of patterns of spatial and temporal yield variability.

Growth analysis and land equivalent ratio of fenugreek-buckwheat intercrops at different fertilizer types

Summary Intercropping can increase crop growth and yield due to improved resource use efficiency. A two-year field experiment was performed in Shahrekord (Iran) to determine the effect of crop stand composition and fertilizer type on the productions of aboveground dry matter and growth parameters of fenugreek-buckwheat intercrops. Sole crops of fenugreek (F) and buckwheat (B) were compared to the three substitutive intercropping ratios (F:B = 2:1, 1:1 and 1:2). Crop stands were fertilized with chemical fertilizer or broiler litter. Fenugreek could produce in intercrops a similar amount of above-ground dry matter compared to its corresponding share on the sowing ratio. Contrary to that, buckwheat could produce in intercrops more above-ground dry matter than its share on the sowing ratio, especially with a low to medium share of buckwheat. Consequently, the intercrops with F:B (2:1) and F:B (1:1) had an above-ground dry matter yield advantage compared to the pure crop stands of both crops. Broiler litter was more effective in increasing the growth rates and thus the above-ground dry matter production compared to the chemical fertilizer. Thus, growing fenugreek and buckwheat in intercrops fertilized with broiler litter can be beneficial for increasing the biomass production in semiarid environments.

Cumulative Impact of Crop Stand and Foliar Urea on Traits of Importance in Sunflower (Helianthus AnnusL.)

In order to assess the cumulative impact of crop stand and foliar urea on sunflower, the experiment was conducted during 2016 (spring). Six treatments were formed with various ha-1 plant populations such as: T1=44289 ha-1 (75×30cm=Control), T2=29526 (75×45cm+foliar urea at development of leaves), T3=36852 (60×45cm+foliar urea at development of flower bud), T4=49284 (45×45cm+foliar urea at flowering completion), T5=55278 (60×30cm+foliar ureaat seed initiation) and T6=73926 (45×30cm+foliar ureaat seed development/maturity). The crop stand and foliar N (urea) application treatments showed remarkable (P<0.05) impact on traits contributing crop growth and yield. On the basis of seed yield ha-1, sunflower sowing in row × plant distance of 60×30cm row× plant distance with 55278 plant population + foliar urea(at seed initiation) showed most promising results grew plants upto166.5cm height having 6.8cm thick stems with more leaves (15.6 plant-1) and bigger seed heads (18.1cm) as well as more (1408.7) and heavier (60.5g) seeds head-1.The seed index was also higher (53.0g) in this treatment leading maximum yields (2181.7kg ha-1) and determined highest oil content (40.1%). Sunflower sown under T6, T4, T1, T3 and T2 ranked 2nd, 3rd, 4th, 5th and 6th in overall yield performance. Generally the crop under wider plant distances with lower per ha-1 populations of 29526 and 36852 showed better growth, but decrease in plant population caused reduction in seed yield; while 60×30cm row × plant distance providing ha-1 plant population of 55278 produced economically higher seed yield when given foliar applied urea at seed initiation.

Grain yield and competitive ability against weeds in modern and heritage common wheat cultivars are differently influenced by sowing density

Sowing density can have a strong impact on crop stand development during wheat growing cycle. In organic and low-input agriculture, and therefore with minimum or nil use of chemical herbicides, increased sowing density is expected to affect not only grain yield but also weed suppression. In this study we tested, under Mediterranean conditions, six common wheat cultivars (three modern and three heritage) and two three-component mixtures (arranged by combining the three modern or the three heritage cultivars). The different crop stands were tested at sowing densities of 250 (low) and 400 (high, similar to standard sowing density used by local farmers) viable seeds m-2 for two growing seasons. We did not detect a significant effect of crop stand diversity (single cultivars vs mixtures) on grain yield and weed suppression. Differences were ascribed to type of cultivars used (heritage vs modern). Compared to high sowing density, in modern cultivars grain yield did not decrease significantly with low sowing density whereas in heritage cultivars it increased by 15.6%, possibly also because of 21.5% lower plant lodging. Weed biomass increased with low sowing density both in heritage and modern cultivar crop stand types. However, heritage crop stands had, on average, a lower weed biomass (56%) than modern crop stands. Moreover, weed biomass in heritage crop stands at low density (6.82 ± 1.50 g m-2) was lower than that of modern cultivars at the same sowing density (15.54 ± 3.35 g m-2), confirming the higher suppressive potential of the former. We can conclude that lower sowing density can be advisable when using heritage crop stands as it keeps productivity while decreasing plant lodging and maintaining weeds under control.

Phenology and Maize Crop Stand in Response to Mulching and Nitrogen Management

Phenology and Maize Crop Stand in Response to Mulching and Nitrogen Management

Remote Sensing of Perennial Crop Stand Duration and Pre‐Crop Identification

Crop sequence history both describes results of on‐farm decision‐making processes and signals potential environmental impacts across landscapes. Remote sensing classifications for 11 yr in western Oregon identified multi‐year production of established perennial crops and successive plantings of annual crops, quantified durations, and defined frequencies of pre‐ and post‐crops for multi‐year production periods. Measuring duration of continuous production of specific crops and characterizing crop sequence patterns required: (i) optimizing year‐to‐year landuse consistency and within‐year landuse classification accuracy, (ii) sufficiently detailed landuse classes to capture 99% of all crops grown in the diverse agriculture of this region, and (iii) enough years of data that majorities of fields experienced at least one full cycle of planting new stands of perennial grass seed crops (or successive plantings of specific annual crops), maintaining those fields in production until their eventual termination, and subsequent planting of new crops. Averaged over all possible starting and ending years between 2004 and 2014, continuous production of the same crop on the same field ranged from highs of 2.9, 4.6, 3.7, and 5.9 yr for perennial ryegrass (Lolium perenne L.), orchardgrass (Dactylis glomerata L.), tall fescue [Schedonorus arundinaceus (Schreb.)], and Italian ryegrass [L. perenne L. subsp. multiflorum (Lam.) Husnot] grown for seed to lows of 2.4 and 1.5 yr for clovers grown for seed and cereal grains. With very few exceptions, pre‐crop frequencies were stable over the period of the study. Variability in perennial ryegrass and tall fescue stand duration included strong local components in which fields with much longer or shorter than average stand durations were often found in close proximity to one another.Core Ideas Crop rotation history can be derived from landuse classifications over multiple years. Perennial grass seed crop stand duration variability localized to individual fields. Frequency at which specific crops followed each other was mostly stable over time.

English

English

Sources of angle-dependent errors in terrestrial laser scanner-based crop stand measurement

In past years, research was conducted to investigate the potential of laser rangefinders and scanners for vehicle-based measuring of crop stand physical parameters. High coefficients of determination (R2>0.90) were found between the crop biomass and the laser rangefinder and scanner readings in the form of the mean height of reflection points of the laser beam. It was observed that the height of the reflection point increased depending on the detecting angle of the laser beam in a considerable manner. This phenomenon indicates that farther crop plants generate higher reflection points, resulting in an overestimation of crop height respectively of crop biomass. In the face of these unsolved problems, the object of the paper was to investigate the measuring properties of a chosen laser scanner depending on the inclination angle and the scanning angle and to analyze the error sources for vehicle-based laser scanner measurements in crop stands. Therefore, the scanner was investigated in two test series (May 30, 2008 in winter wheat, and June 10, 2009 in winter rye) along a transect (tramline) with a length of approximately 700m. The performed comparisons demonstrated that one part of the observed overestimation of the reflection point height can be explained theoretically by the geometry of the laser beam. The main part of overestimation was explained by the recognizability of the gap fraction in crop stands. Because no sufficient theoretical compensation algorithm for overestimation resulting from gaps exists, it must be concluded that for each specific laser rangefinder type and crop species, the overestimation depending on detection angles has to be investigated individually in field tests.

Ranging Sensors for Vehicle-Based Measurement of Crop Stand and Orchard Parameters: A Review

In agricultural crop production, information important for optimizing production processes (precision farming) and reducing the environmental impact can be obtained from soils and plants with sensors. Ranging sensors are utilized in research activities that use remote-sensing techniques. In this work, three types of ranging sensors or measuring principles (light detection and ranging (LiDAR), radar, and ultrasonic) are evaluated for practical use with agricultural machinery to improve production processes. In the first part of this article, the fundamentals of the prescribed measuring principles are described. Based on the relevant literature, state-of-the-art sensor groups for measuring morphologic crop stand and orchard parameters are presented and discussed in the second section. In the third section, the sensors are assessed regarding their suitability for installation on agricultural machinery under field conditions; specifically, their functional parameters are evaluated (e.g., working distance, mounting height, inclination angle, resolution, and measurement frequency) along with experimental data obtained in scientific investigations. The positive test results in the application of the measuring principles presented in previous publications are reviewed and, based on a summary assessment, the LiDAR measuring principle is indicated as the preferred solution for vehicle-based measurement of crop stand and orchard parameters.

Impact of Seed Treatments on Crop Stand Establishment

S eeds of field-sown crops often are exposed to adverse environmental conditions during germination, emergence, and seedling development. Several environmental and seed physiological factors interact with these growth stages and contribute to the relative success of crop production. Advances in seed priming, coating, pathogen control, and various combinations of other presowing seed treatments show promise for improvement of crop stand establishment. The need for reliable and uniform crop establishment in horticultural production systems is well recognized (Herner, 1986; Heydecker and Coolbear, 1977; Gray, 1978; Matthewsand Powell, 1986). After the many steps involved in seed production, harvesting, milling, and storage, the ultimate indicator of a seedlot’s quality is its performance upon sowing in the field or greenhouse. Factors that limit stand establishment includesoil crusting, poor seed/soil contact, excessively high or low temperatures, seed-borne/soil-borne pathogens, and deficient or excessive soil moisture. In the face of these environmental stresses, achieving acceptable seed germination and emergence (and transplant survival) is no small task in stand establishment. This paper discusses the scope and impact of several types of seed treatments that can improve crop establishment.

Effect of Seed Treatment on Crop Stand of Direct Seeded Rice

Effect of Seed Treatment on Crop Stand of Direct Seeded Rice

Modelling the Vertical Variability of the Radiation Flux Density in a Closed Green Crop Stand

AbstractAs the incident radiation penetrates vertically in any plant stand having green closed canopy, the PAR flux density (Rn) gradually decreases with depth in a manner that the radiation flux density (Rn) is inversely proportional to the photosynthetic‐area percentage (Pap), and the radiation interception density (Rid). The radiation interception density (Rid) is a function of net radiation intercepted, total photosynthetic‐area percentage and the thickness of that photosynthetic‐area.

Improvement of Crop Stand in Flooded Rice Fields

Improvement of Crop Stand in Flooded Rice Fields

Fertilizer Placement for Small Grains in Relation to Crop Stand and Nutrient Efficiency in Nebraska

AbstractTime and method of fertilizer nutrient application have been found to markedly influence stand and growth of small grains in Nebraska. Severe stand reductions and yield losses have been noted as a result of moderate rates of N as well as K applied with the seed. These losses do not occur every year, nor are they uniform across the state in the years when noted. On the other hand, efficiency of applied P usually has been much greater when applied with the seed than by other methods.Investigations in the field and constant temperature laboratory suggest a low moisture level at which the most serious damage of fertilizer salts to germination occurs, but full germination is not assured at any soil moisture level without a surface increment to leach fertilizer away from the seed. Emergence loss from N adjacent to the seed at low moisture level is in direct proportion to the time interval before rain or irrigation raises the level. In general, N materials are more detrimental per unit weight than K, and the latter more than P. Damage to germination under critical soil moisture is apparent at 10 lbs. N/acre, increasing to the point of stand elimination with 160 lbs. N/acre. Among N carriers, CaCN2 and NH4OH are most deleterious to germination followed by CO(NH2)2 &gt; NaNO3 &gt; KNO3 &gt; (NH4)2SO4 &gt; NH4NO3. Straight carriers of phosphate cause little damage, but ammonium phosphates of 1:1:0 ratio are harmful when placed with the seed under conditions of limited moisture; the damage is less with pelleted than finely ground material. Fertilizer and seed need not be in immediate contact for germination inhibition, as evidenced by appreciable migration of N and P to the imbibing seed.Soil microorganisms are in part responsible for fertilizer injury to germinating seed, occasioned by their greater tolerance of low moisture supply and high salt concentration. Seed treatment at the lower moisture levels alleviates but does not eliminate the fertilizer detriment.Phosphorus placement with the seed of small grains is desirable in the drier regions so long as the N concurrently added with the seed does not exceed 10 or 15 lbs./acre. Supplementary N is essential to maximum P fertilizer utilization, but much of it should be applied separate from the seed.