Crop Cycle Research Articles

Sowing of stevia (Stevia rebaudiana Bertoni) in the humid tropical climate of Tabasco, México

Objective: To evaluate Stevia rebaudiana under the climatic conditions of the state of Tabasco, Mexico. Design/Methodology/Approach: Three consecutive sowings of stevia plants were carried out for one year, progressively adapting the management and crop establishment according to the results obtained in the previous sowing. The survival percentage at 15 days after transplantation (dat) was calculated. Plant height was measured at 60 days and limitations observed in each crop cycle were recorded, as well as climatic variables. Results: bending problems, soil splashing on the leaves, and foliar fungal diseases were recorded during the December 2019 sowing; however, 71% of the plants survived the transplant. In the April 2020 sowing, 40% of the plants survived the transplant; nevertheless, the plants showed generalized chlorosis and lack of growth, as a consequence of excessive solar radiation. Finally, in August 2020, the survival rate reached 89% and an average plant height of 20.55 cm was recorded. Study Limitations/Implications: the rainfall that caused flooding in June and October 2020 limited the development of this research. Likewise, to determine the steviosides content and establish the quality of the harvest, the cultivation cycle must conclude. Findings/Conclusions: Stevia can be grown in the climatic conditions of Tabasco, as long as the rainy seasons and high temperatures are avoided during the first stage of cultivation. Water is a limiting factor that causes phytopathological problems and the death of the plant.

Yield and related traits of three legume crops grown in olive-based agroforestry under an intense drought in the South Mediterranean

Heat and drought stresses have become more frequent and intense in the Mediterranean, strongly influencing arable crop phenology, growth, and grain yield. Agroforestry systems can effectively buffer the adverse climate conditions and stabilize or even increase crop yield under climate change. However, the positive effects of agroforestry remain uncertain due to the possible intense competition between trees and crops, especially for legume crops that have been less studied than cereals in such context. This study aimed to assess the response of the phenology, growth, grain yield, and yield-related traits of chickpea (Cicer arietinum), faba bean (Vicia faba), and lentil (Lens culinaris) to olive-based agroforestry (AFS) as compared to sole crops system (SCS) in the South of the Mediterranean. We conducted a field experiment during two growing seasons marked by an intense drought, either at the beginning (year 1) or at the end (year 2) of the crop cycle. Crop growth and yield were lower in year 1 than in year 2, reflecting the adverse growing conditions caused by the early drought. They were also lower in AFS than in SCS for both years, indicating that trees had competitive effects on crops. In year1, the yield loss of grains in AFS was 66 % for lentil, 47 % for chickpea, and 43 % for faba beancompared to SCS, confirming the greater shade sensitivity of lentil. In year 2, the reduction was significantly smaller and was about 46 %, 34 %, 38 % for lentil, chickpea and, faba bean, respectively. The number of pods and grains were the most affected yield components by agroforestry and drought timing across the three legumes crops. Similar responses were found when comparing crops at differentdistances to trees within the AFS field. Crops generally had lower biomass and yield, explained by fewer pods and grains, on the northern side of trees compared to the southern side of trees or the middle of tree inter-rows, causing significant spatial heterogeneity in crops. However, lentil and chickpea had apositive response to shade during the early drought year while a negative response during the late drought year, suggesting that the benefits of the microclimate created by olive trees express dependingon drought timing and crop physiology. Our study supports legume integration into AFS, suggestingthat chickpea should be considered during high-stress conditions, while faba bean should be preferredduring low-stress conditions.

POSITIONING OF WHITE OAT CULTIVARS IN DIFFERENT ENVIRONMENTS FOR HIGH GRAIN PRODUCTIVITY IN ORGANIC SYSTEM

<p><strong>Background. </strong>White oat is a multifunctional species with significant benefits to human health, so the positioning of genotypes in the organic system is substantial to promote the expression of maximum productive potential. <strong>Objective.</strong> To select and identify the genotypes with greater stability and productive adaptability. <strong>Methodology.</strong> The study was carried out in 11 environments located in the countries of Brazil (states of Rio Grande do Sul and Paraná) and Paraguay (Itapúa) in 2019 and 2020, evaluating in each of them four genotypes of white oats (<em>Avena sativa</em>) (URS Corona, URS Brava, IPR Artemis and IPR Afrodite) each considered as treatments. The experimental design was randomized blocks with four replications per treatment. The variables analyzed were grain yield (GY, kg ha<sup>-1</sup>) and the cycle in days from emergence to physiological maturity (PM). With the presence of G x E interaction, AMMI and GGE biometric methods were used to study adaptability and stability. <strong>Results.</strong> With the data obtained, it was possible to form three mega-environments with the identification of specifically adapted genotypes. The URS Brava genotype was characterized as the ideal genotype, with high stability and wide adaptability for grain yield, which can be positioned in all environments. High altitudes promoted a longer crop cycle and lower grain yield, while low altitudes induced a shorter cycle and grain yield maximization of white oat genotypes. <strong>Implications.</strong> The current results indicate that it is possible to position a single genotype within a region formed by similar environments, as well as it was identified that the crops should preferably be carried out in regions of lower altitudes. <strong>Conclusion.</strong> The URS Brava genotype is considered the ideal genotype with high potential for productivity at low altitudes.</p>

Effect of Greenhouse Film Cover on the Development of Fungal Diseases on Tomato (Solanum lycopersicum L.) and Pepper (Capsicum annuum L.) in a Mediterranean Protected Crop

Greenhouses on the Mediterranean coast mainly use plastic materials as their cover. The influence of light exerted by these materials directly affects the crops by modifying the environment in which they develop. The aim of this study was to analyze the effect of the use of two plastic films in an experimental greenhouse on the development of fungal diseases in two spring–summer crop cycles: tomato (Solanum lycopersicum L.) from February to July 2021 and pepper (Capsicum annuum L.) from February to July 2022. The study was carried out in Almeria (Spain) in a multispan greenhouse divided transversely into two sectors by a polyethylene sheet. A commercial film was installed in the east sector (90% of transmissivity and 55% diffusivity) and an experimental film was installed in the west sector (85% of transmissivity and 60% diffusivity). In addition, the effect of the yield and quality of the harvested fruit was determined. In this study, two diseases were established naturally on the crop: (i) powdery mildew (Leveillula taurica) in both the tomato and the pepper crop cycles and (ii) early blight (Alternaria solani) in the tomato. The analyses of both diseases showed that the areas of the greenhouse that used the plastic cover, which presented a lower sunlight transmissivity, showed higher levels of disease than the areas that used the plastic cover that allowed greater transmissivity of light within the greenhouse, differing statistically in some phases of the crop. The marketable yield was 4.2% (for tomato) and 3.1% (for pepper) higher in the sector with the experimental film with high transmissivity. For both crops, the quality of the fruits did not show statistically significant differences.

Passaging Phyllosphere Microbial Communities Develop Suppression Towards Bacterial Speck Disease in Tomato

Microbial community-based disease management approaches have the potential to substitute or combine with currently employed strategies. Suppressive soils are great examples of microbial communities that suppress soilborne plant disease after severe outbreaks and are maintained over multiple years or crop cycles. Although there are many suppressive soil examples, to our knowledge, there are no descriptions of disease-suppressive phyllosphere communities. Therefore, we investigated whether a phyllosphere microbial community could be developed through a selective passaging method to suppress disease using the model pathosystem of Pseudomonas syringae pv. tomato ( Pto) and tomato. Field tomato phyllosphere microbial communities were recovered and spray transferred to greenhouse tomato plants, after which they were inoculated with Pto. Disease severity was visually estimated and the microbial communities were recovered to be independently applied to the next passage. Overall, greenhouse passaging resulted in an increase in disease severity for all passage lines from the initial passage, which peaked at passage 4 to 5, followed by a sharp decline until passage 9. The disease severity at passage 9 was also significantly lower than a non-passaged Pto-only comparison. Heat treatment of passage 9 communities resulted in elevated disease severity over several subsequent passages in the growth chamber, whereas the untreated community maintained low disease. Community-only passage lines (without Pto inclusion during passaging) did not show disease suppression after subsequent pathogen introduction. This work presents an experimental approach to develop phyllosphere microbial communities in the presence of a phytopathogen to enrich for a low disease phenotype and results in maintained disease suppression. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Influence of Climatic Variables on Incidence of Whitefly-Transmitted Begomovirus in Soybean and Bean Crops in North-Western Argentina.

Over the last 20 years, begomoviruses have emerged as devastating pathogens, limiting the production of different crops worldwide. Weather conditions increase vector populations, with negative effects on crop production. In this work we evaluate the relationship between the incidence of begomovirus and weather before and during the crop cycle. Soybean and bean fields from north-western (NW) Argentina were monitored between 2001 and 2018 and classified as moderate (≤50%) or severe (>50%) according to the begomovirus incidence. Bean golden mosaic virus (BGMV) and soybean blistering mosaic virus (SbBMV) were the predominant begomovirus in bean and soybean crops, respectively. Nearly 200 bio-meteorological variables were constructed by summarizing climatic variables in 10-day periods from July to November of each crop year. The studied variables included temperature, precipitation, relative humidity, wind (speed and direction), pressure, cloudiness, and visibility. For bean, high maximum winter temperatures, low spring humidity, and precipitation 10 days before planting correlated with severe incidence. In soybeans, high temperatures in late winter and in the pre-sowing period, and low spring precipitations were found to be good predictors of high incidence of begomovirus. The results suggest that temperature and pre-sowing precipitations can be used to predict the incidence status [predictive accuracy: 80% (bean) and 75% (soybean)]. Thus, these variables can be incorporated in early warning systems for crop management decision-making to reduce the virus impact on bean and soybean crops.

A real-time decision-making tool based on dynamic thresholds for Phthorimaea absoluta management in greenhouse tomato

The onset of digital information and computing power brings the opportunity to optimize the use of agricultural inputs and favors the transit to an information-based agriculture. The tomato leafminer (TLM), Phthorimaea absoluta, is a major pest of greenhouse tomatoes, and its control relies heavily on chemical pesticides. This study presents a decision-making system for TLM that dynamically adjusts decision thresholds throughout the crop cycle. Through a controlled experiment, we obtained pest damage curves for three crop phenological stages, which were used to derive a set of non-linear functions that estimates a decision threshold expressed as the maximum tolerable number of larvae/plant for any given crop age. We show that produce losses due to TLM are far from constant across the crop cycle, and that such variation can be modeled as a function of the effect of TLM on yield, cumulative control costs, potential yield, and produce prices. The decision threshold function was linked to a previously validated sampling plan, which was adjusted to work in serial bouts in frequencies that vary according to sampling results and pest growth rates. The decision-making system is presented as a web-based app that delivers a management recommendation, the timing for the next sampling bout, and an indication of how close the population is from the threshold. This study presents a step forward towards a modern application of the economic injury level concept by adapting pest management decision criteria to the changing ecological and economic context of each production system.

Legume growth and straw retention in sugarcane fields: Effects on crop yield, C and N storage in the central-south Brazil

Large amounts of straw are remained in the sugarcane fields after the crop to be mechanically harvested. Straw is pointed out as a feedstock to attend high bioenergy production demand. However, either indiscriminate straw removal or high amount of straw kept on the field may impair several soil functions and thereafter decreases plant tillering and crop yield. Better nutrients cycling and soil physical protection due to Leguminosae species grown within the sugarcane renewal period may offset implications of straw managements across the crop cycles. Thus, does Crotalaria sp. grow within the sugarcane renewal period can offset the undesirable implications of unsustainable straw management on soil and crop yield? To address this research question, a two-year experiment was carried out in Quirinópolis, Chapadão do Céu, Iracemápolis and Quatá, first two sites are in Goiás state, while the other sites are in São Paulo state, Brazil. Soil and plant parameters under straw retention rates (i.e., 0%, 50% and 100% of straw retention) were assessed. This management was coupled with fallow (F) and Crotalaria sp. (CR) grown within the sugarcane renewal period. Soil parameters evaluated included, carbon (C) and nitrogen (N) stocks, while stalk yield was plant parameters assessed. The straw retention implications on soil and plant were site-specific. Carbon and N stocks in the upper 0.4 m soil layer were, respectively, 3.5 and 3.1 time higher at the fine-textured soil than the stocks of those elements at the coarse-textured soil. Regardless of Crotalaria sp. grown, stalk yield increased (ranged from 3 to 16 Mg ha−1) under total straw retention rate for most sites, while in the coolest site 50% and 100% straw retention reduced stalk yield in 13 and 14 Mg ha−1, respectively. In addition, Crotalaria sp. grown within the sugarcane renewal period does not seem able to avoid reduction on soil N availability due to straw retention along the ratoon cycles. Overall, straw removal for bioenergy should be judiciously performed, according to local edaphoclimatic conditions.

Critical Review on the Inclusion of the Measurement of Nitrogen Produced in Short Incubations (Nan) in the Diagnostic Protocol of Nitrogenous Fertility in Cordoba (Argentina)

N is the nutrient that is applied in the greatest quantity to increase crop yields. Having a soil analysis that allows estimating the N needs of the crop would have economic and environmental benefits. The measurement of total C, total N and the content of N-nitrates are part of the analytical protocol that is carried out in pre-sowing for diagnostic purposes. However, the relationship between these measurements and actual N mineralization in the field is only approximate. To improve the estimation of N availability, it is necessary to consider the initial inorganic N and the mineralized N (Nmin) during the growing season. The search for an accurate predictor of Nmin that can be done quickly in the laboratory has sparked interest in measuring N in short anaerobic incubations or Nan. In this article, the soil properties that intervene in the N mineralization process that affect the measurement of Nan are exposed to know the scope: advantages and disadvantages of the inclusion of Nan in the routine protocol for diagnostic purposes for its use as a predictor of mineralized N during the crop cycle.

Bioactive Compounds, Antioxidant Activity, and Mineral Content of Wild Rocket (Diplotaxis tenuifolia L.) Leaves as Affected by Saline Stress and Biostimulant Application

The availability of irrigation water of good quality is decreasing due to soil salinization and the deterioration of aquifers. Moreover, ongoing climate change severely affects crop production and necessitates the intensification of cropping systems in order to ensure food security at a global scale. For this purpose, the aim of the present study was to evaluate the mitigating effects of two natural biostimulants on Diplotaxis tenuifolia L. plants cultivated at different salinity levels (EC of 0 dS m−1, 2 dS m−1, 4 dS m−1, and 6 dS m−1) and harvested at six consecutive cropping cycles. The tested factors showed a varied combinatorial effect on the tested parameters. These findings indicate the importance of considering growing conditions and cropping periods when applying biostimulants in D. tenuifolia plants under salinity stress. Antioxidant activity and bioactive compounds, such as total phenols, carotenoids, and total ascorbic acid, were variably affected by salinity, biostimulant application, and harvesting time, while mineral profile was also affected by the tested factors depending on the combination of factors. Finally, nitrate content showed decreasing trends with increasing salinity, while biostimulant application resulted in the higher accumulation of nitrates compared to the untreated plants. Although biostimulant application seems to alleviate the negative effects of salinity stress, the effect of growing conditions, as indicated by successive crop cycles, is also important for the response of D. tenuifolia plants to saline conditions and biostimulant application.

Effect of Compost Derived from Urban Waste on Chard (Beta vulgaris L., var cycla) Yield and Soil GHG Fluxes in a Mediterranean Agricultural System

The use of recycled materials as soil amendments and fertilizers is an important priority in the agronomic sector to valorize waste from a circular economic perspective and reduce waste disposal, reduce dependence on external inputs, and provide better climate change mitigation options. In this study, we evaluated the agroecological performance of compost derived from recycled organic matrices of urban waste (mixed composted amendment, MCA) of the metropolitan area of Rome. MCA is available in big quantities and might represent an interesting option to substitute conventional mineral nitrogen fertilizer (CF). The effect of MCA, CF, and a combination of both (MIX 1:1) was tested on crop yield and greenhouse gas emissions in a field trial on a common Mediterranean crop (Swiss chart, one season, two crop cycles). The MCA effect on crop yield was positive and comparable to CF and MIX treatments, while MCA treatment showed the lower soil mineral nitrogen (N) content. GHG emissions in the MCA treatment were comparable to those observed in CF and MIX, being overall quite low. The soil acted as a weak net CH4 sink in all treatments (−12.6 ± 6.1 μg CH4 m−2 h−1); no differences in CO2 emissions between MCA and CF or MIX treatments were observed (range 0.1−0.2 g m−2 h−1). The N2O emission intensity of MCA was slightly lower than MIX and CF treatments (0.09, 0.011, and 0.011 g N2O kg−1 crop dry weight, respectively). Overall, MCA seemed a valid alternative to CF for the tested agro-environmental indicators in the spring/summer Mediterranean conditions.

Efficacy of sewage sludge derived biochar on enhancing soil health and crop productivity in strongly acidic soil

Converting sewage sludge to biochar to serve as soil amendment and nutrient supplement to cropland may be an environmental benign and value-added approach to recycle the waste. Potting experiments were conducted to examine the efficacy of sludge biochar amendments on enhancing soil health and crop productivity. Strongly acidic soil (pH=5.0) was amended with sludge biochar at three different concentrations: 0 (control), 1% and 2% of its dry weight, and packed into plastic buckets (9.45-L) to a bulk density of 1.1 g cm-3, and each treatment had three replicates. Winter wheat (Triticum aestivum L.), spinach (Spinacia oleracea), and Mung bean (Vigna radiata) were sequentially grown for nine months under greenhouse and field conditions (each crop cycle lasted three months). The above-ground biomass was collected, and oven dried at 65°C for 72 hours to assess plant biomass yield. Soil health parameters such as aggregates stability, pH, electric conductivity (EC), soil respiration, and microbial biomass C were measured. Soils amended with 2% biochar demonstrated higher biomass yield in winter wheat and spinach crops compared to those amended with 1% biochar and unamended control, on the other hand, mung bean did not present significant difference in all treatments. Similarly, 2% biochar demonstrated high aggregates stability (19.85%) followed by control (9%) and 1% biochar (8.3%). Soil acidity was neutralized in soils amended with 2% biochar (pH: 6.5) compared to control (pH: 5.8) and 1% biochar (pH: 5.5). EC was in the ideal level (<2.7 dS m-1) for all treatments. Soil respiration was not significantly different in all treatments. Microbial biomass C was higher in control and 2% biochar with significant differences towards 1% biochar. These findings provide additional evidence that sludge biochar promote plant growth and improve certain soil health parameters. However, the effect of sludge biochar in soil biological properties was not observed. Therefore, long-term field experiments are needed to assess the amendment effect of sludge biochar on microbial biomass C and soil respiration to validate the persistent efficacy of sludge biochar amendments on facilitating crop production, crop productivity, and soil health.

What drives wind erosion in cropped areas? A case study in southern Tunisia

Dust emission by wind erosion is a worldwide phenomenon that threatens sustainable development and population wellness in areas where anthropogenic activities develop. However, uncertainties on the current estimates of dust originating from agricultural activities remain high. This study aims at disentangling the respective roles of meteorology, surface properties, and human practices in the dynamics of wind erosion over croplands. Therefore, an experimental field campaign was conducted in a traditionally cultivated barley field in southern Tunisia during the agricultural year 2015–2016. Meteorological parameters (wind speed and direction, rainfall), surface characteristics (barley surface cover and height), and the horizontal flux of aeolian sediments were measured. Land management was also documented. 97% of the wind erosion fluxes occurred between mid-May and November 2016. This was explained by the seasonal cycle of barley crop, land management, and meteorological conditions: (i) in autumn, the soil surface sufficiently wet to allow barley growth is tilled, which creates clods that increase the soil surface roughness and inhibits wind erosion, (ii) late winter coincides with the period of the highest wind speed but the height of the barley, maximal in this period, prevents wind erosion, and (iii) the field surface left bare and trampled at the end of harvest in spring is totally prone to wind erosion. This study highlights the importance of accounting for the joint seasonality of the meteorological parameters, vegetation cover, and human practices when studying wind erosion. Neglecting one of these parameters can induce a net overestimation/underestimation of wind erosion by the models.

Grain yield, yield components and nitrogen economy of irrigated second-crop common Buckwheat (Fagopyrum esculentum Moench) in a cold-temperate region

Common buckwheat (Fagopyrum esculentum Moench) is a species with great nutritional value and promising to be cultivated as a second crop in irrigated fields of cold-temperate regions with short growing seasons. However, little information exists regarding the nitrogen (N) economy of common buckwheat as a second crop following a high-yielding winter cereal. This study aimed to quantify grain yield, its components, and the grain protein content, and to evaluate N economy processes such as the initial N use efficiency (INUE), the N uptake efficiency (NUptE), the N internal efficiency (NIE) for biomass and grain yield and the N harvest index (NHI) among different treatments of N availability at sowing in four site-year experiments of common buckwheat as a second crop in irrigated fields of the southwestern Pampas of Argentina. The variety Mancan, used in this study, lasted between 73 and 92 days (888–1073 °C days) from sowing to harvest. Grain yield was highly correlated with achene number but not with achene weight. Grain yield ranged from 405 to 2725 kg ha-1, with an interaction between treatments and experiments, with major differences among experiments and minor differences among N availability treatments. Relative N uptake was maximized at a higher value of N availability (160 kg N ha-1) than grain yield (50 kg N ha-1), associated with higher responses of N uptake, vegetative N uptake and grain protein content than grain yield to N availability. However, NUptE featured a negative response to N availability in all experiments. NHI was highly variable among experiments, ranged between 0.51 and 0.83 and was affected by N availability in only two experiments. NIE for biomass and grain yield were 80 kg kg-1 and 36 kg kg-1, respectively, which were lower than those of most cereals but higher than those of other non-cereal grain crops. A short crop cycle of the variety Mancan, an average grain yield of 1594 kg ha-1 among experiments in this study, a low N availability requirement to maximize grain yield and high values of NIE for biomass and for grain yield suggest that buckwheat is a promising species for second crop sowing in cold-temperate regions.

Intercropping systems between broccoli and fava bean can enhance overall crop production and improve soil fertility

Legumes can be regarded as a good alternative in intercropping systems to increase soil fertility and biodiversity whilst enhancing crop production and reducing fertilizer use. The aims of this study were to: i) assess whether crop yield, crop quality and soil physicochemical properties can be improved using different intercropping patterns between broccoli (Brassica oleracea var italica) and fava bean (Vicia faba) compared with their respective monocrops, all grown under organic management; and ii) assess if fava bean grown as an intercrop can partially replace fertilizer use without negative effects on crop production. We compared, for three crop cycles, monocrops with three different broccoli-fava intercropping patterns: mixed intercropping, row intercropping 1:1 (broccoli:fava), and row intercropping 2:1 (broccoli:fava). Fertilization was reduced by 30% in the diversified plots. After three crop cycles, the results showed that the intercropping systems, regardless of the pattern, kept soil organic C levels, while they significantly decreased in broccoli monoculture. Intercropping also significantly increased soil total N, available P and exchangeable K (0.13%, 39 mg·kg−1 and 364 mg·kg−1, respectively), compared to the broccoli monocrop (0.11%, 11 mg·kg−1 and 277 mg·kg−1). Total production was significantly higher under the diversified systems, which doubled the overall yield of the monocrops every crop cycle, with land equivalent ratios > 1. Hence, the introduction of fava bean associated to broccoli could be considered a feasible strategy for sustainable agriculture, with environmental gains and economic savings for fertilizers and water.

Co-Composted Chicken Litter Biochar Increases Soil Nutrient Availability and Yield of Oryza sativa L.

Intensified cultivation of rice has accelerated weathering of most tropical acid soils leading to significant loss of base cations. In most developing countries, rice yield is low and this results in its production being costly because productivity versus labor is low. The objectives of this study were to (i) enhance soil chemical properties, nutrient uptake, and grain yield of rice grown on a mineral tropical acid soil using agro-wastes; (ii) determine the agro-waste (chicken manure, cow dung, forest litter, and Leucaena) that has the potential to significantly increase rice yield; and (iii) determine the residual effects of the organic soil amendments produced from the agro-wastes on soil and rice productivity. The treatments used in this three-cycle field study were (i) soil without amendments (S0); (ii) prevailing recommended rates for fertilizers (NPK-Mg); (iii) biochar–forest litter compost (OSA1); (iv) biochar–chicken litter compost (OSA2); (v) biochar–cow dung compost (OSA3); (vi) biochar–Leucaena compost (OSA4); and (vii) biochar–Leucaena–chicken litter compost (OSA5). Standard procedures were used to determine the plants’ rice growth, grain yield, plant nutrient concentrations and uptake, and selected soil chemical properties. The use of organic soil amendments (OSA1 to OSA5) significantly improved the soil chemical properties, rice plant growth, nutrient uptake, and grain yield compared with the prevailing method of cultivating rice (NPK-Mg). The application of organic soil amendments reduced the use of inorganic N, P, K, MgO, and trace elements fertilizers up to 25%, 100%, 64%, 100%, and 100%, respectively. The organic soil amendments with Leucaena significantly increased rice grain yield of OSA5 at 11.17, 13.11, and 10.06 t ha−1 in the first, second, and third cropping cycles, respectively. The residual effect of the organic soil amendments also improved rice plant growth, nutrient uptake, and rice grain yield although these were slightly reduced as compared to those of the two previous cropping cycles, the afore-stated treatments were superior to the prevailing method of cultivating rice (NPK-Mg). Transforming agro-wastes into organic soil amendments can improve tropical mineral acid soils and rice productivity.

Change in soil chemical attributes and yield of a common-bean crop in response to steel slag application

Most agricultural soils in Brazil are classified as acid, which limits agricultural production in the country, warranting the application of acidity correctives. The present study examined the effect of steel slag application on chemical characteristics of the soil as well as on the metabolic responses and yield of common-bean plants in a no-till system. The experiment was laid out in a randomized-block design with 42-m2 subplots in a 7×2 factorial arrangement, with four replicates. Treatments consisted of two factors, namely, acidity correctives and application forms. The following correctives were tested: steel slag (T1), wollastonite (T2), ladle furnace slag (T3), stainless steel slag (T4), calcined agricultural limestone (T5), agricultural limestone (T6), and a control without correctives (C). The application forms were surface application and incorporation (20 cm). Ten months after the last reapplication of the acidity correctives, a soil probe sampler was used to collect samples from the 0–10 cm, 10–20 cm, and 20–40 cm layers for chemical analysis. The common-bean crop was established after 16 months of the applications, and the following parameters were evaluated 40 days after germination: plant height; leaf dry weight; relative water content; electrolyte losses; pigment content (Clo a, Clo b, and carotenoids); leaf macronutrient and micronutrient content; total soluble protein content; leaf silicon content; enzyme activities of superoxide dismutase, peroxidase, and catalase; and gas exchange. At the end of the crop cycle, grain production and yield components were evaluated. Phosphorus, pH, base saturation, and Si increased with the application of silicates, influencing the number of plants m-1 and 100-grain weight; however, grain yield did not change

RENDIMIENTO DE BANANO DÁTIL EN SISTEMA DE CALLEJONES DE Inga spp., A DIFERENTES DOSIS DE FERTILIZANTES DE POTASIO Y FOSFORO

<p><strong>Background: </strong>the agronomic yield of crops of importance for rural households in the humid tropics, such as banana, cultivated in association with leguminous trees, such as Inga spp., must be studied because of the little available information on that association, especially with regards to yield response to the application of P and K under agroforestry systems, and the interaction between organic (leguminous residues) and inorganic sources of nutrients. <strong>Objective: </strong>the objective of this study was to evaluate the yield of lady finger banana alley cropped with <em>Inga</em> spp., under several levels of natural fertilizers such as K<sub>2</sub>SO<sub>4</sub> + Mg, and phosphoric rock (RF). <strong>Methodology: </strong>Yield response of lady finger banana (<em>Musa acuminata </em>Colla) under an alley cropping system with guama (<em>Inga</em> spp.). Prior to the establishment of the crop, dolomitic lime (Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>CaF<sub>2</sub>) at a rate of 2 ton ha<sup>-1</sup> was applied. In addition, phosphoric rock (RF) was added to the crop at diverse levels (0, 20, 40, 80 kg ha<sup>-1</sup>), and potassium sulphate and magnesium (K<sub>2</sub>SO<sub>4</sub> + Mg) at three levels (0, 45, 90 kg ha<sup>-1</sup>) with five replicates in a total of 35 alleys for treatments. <em>Inga</em> spp. trees provided with nitrogen (N). Two crop cycles were evaluated, cycle 1 (2015) and cycle 2 (2017). <strong>Results: </strong>the highest average weight per bunch were obtained with 80 FP and 0 RF in the first cycle, and with 90 K and 45 K in the second cycle, which were significantly higher than other levels. The highest yield on yearly basis was 45 K among the treatments during the first cycle, and the highest yields during the second cycle were obtained with 45 y 90 K<sub>2</sub>SO<sub>4</sub> + Mg. <strong>Implications:</strong> There are no prior studies for lady finger banana crop associated with <em>Inga </em>spp. trees under alley cropping, this reflects that the study is an original contribution to nutrient-response studies under agroforestry system with Inga. <strong>Conclusion:</strong> the highest yields were obtained with 90 and 45 kg ha<sup>-1</sup> of potassium sulphate and magnesium. The application of dolomitic lime promoted P and K availability for the crop, and better use of applied K<sub>2</sub>SO<sub>4</sub> + Mg and of RF in the treatments.</p>

Effect of sterile rice spikelets derived biochar amendment on nutrient leaching and availability in paddy soil under continuous standing water

ABSTRACT Undisturbed soil columns were used to study the effect of sterile rice spikelets-derived biochar (SRSB) on NH4 +-N, available P, and available K leaching and nutrients availability in a paddy soil under continuous standing water (CSW) condition. The experiment was conducted for two crop cycles and comprised of three treatments: recommended dose of sole chemical fertilizers (CF), CF+SRSB (2 t ha−1), and control. In both crop cycles, incorporation of SRSB reduced the leachate NH4 +-N and available K concentrations, while increased the available P concentration compared to sole CF. The SRSB amendment reduced the cumulative losses of NH4 +-N by 35–38% and available K by 23–25% than CF only. However, there was no significant variation in cumulative available P loss between SRSB and CF only. The reduced leaching loss of NH4 +-N and available K could be attributed to the better nutrient adsorption capacity of SRSB. After completion of two crop cycles, the soil pH, soil organic carbon, soil total N, available P, and available K increased with SRSB amended soils than sole CF. This study showed positive effects of SRSB on retaining nutrients and increasing their availability in the soil which could benefit efficient fertilizer management in paddy soil under CSW.

Cover Crops for Managing Root-Knot Nematodes

Cover crops are grown between cash crop cycles or incorporated with cash crops to improve soil fertility and struc­ture, decrease soil erosion, and suppress weeds, insects, nematodes, and other plant pathogens. Cover crop residues can be incorporated as “green manure” to increase soil fertility for the next crop. Cover crops also help to enhance many beneficial organisms and may contribute to carbon sequestration. They help curtail the spread of nematodes because nematodes cannot migrate to another field if a cover crop is not a host to them. Instead, some of them may starve, which helps to manage their population. Fallow soil also helps keep nematode populations lower, but it may lead to erosion and other problems. Many different types of cover crops are adapted for cultivation in the southern United States, including cowpea, sorghum-sudangrass, sunn hemp, marigolds, jointvetch, sesame, grasses, rye, wheat, oats, crimson clover, vetch, lupine, and, of late, legumes.