Diverse production systems affect soil phosphorus forms and crop productivity in tropical soil

The influence of plantation age on the chemical properties of acidic soils was studied in 16 plots in adult <em>Pinus pinaster</em> stands established in Galicia (NW Spain). The Al fractions in the soil solid phase and the total Al in soil solution were determined in the upper soil layer (0-20 cm) and the lower soil layer (20-40 cm) in each plot. The pH, total C and N, exchangeable Ca, Mg, Na, K, and Al and Al saturation (% Al) were determined in the solid fraction. Aluminium was extracted from the solid phase with the following solutions: ammonium oxalate (Al<sub>o</sub>), sodium pyrophosphate (Al<sub>p</sub>), copper chloride (Al<sub>cu</sub>) and ammonium chloride (Al<sub>NH4</sub>). The total Al in the liquid phase was also determined. All soil chemical parameters, except total N, C/N ratio and % Al, were significantly influenced by soil depth. The mean pH was lower in the upper than in the lower layer (4.57 vs. 4.97), but the opposite was observed for the organic C (77.2 vs. 50.4 g kg<sup>-1</sup>), the effective cation exchange capacity (eCEC) (9.43 vs. 6.25 cmol<sub>(+)</sub> kg<sup>-1</sup>), P (8.95 vs. 4.65 mg kg<sup>-1</sup>) and the exchangeable cations. Organic matter, total N and eCEC were significantly and positively correlated with plantation age (r = 0.69 in the upper layer and r = 0.82 in the lower layer, p < 0.01; r = 0.62, p < 0.05 in the upper layer and r = 0.78, p < 0.01 in the lower layer; r = 0.77, p < 0.01 in the upper layer and r = 0.85, p < 0.0001 in the lower layer, respectively), and pH<sub>KCl</sub> was negatively correlated with plantation age (r = -0.55 in the upper soil layer and r = -0.61 in the lower soil layer, p < 0.05). The concentrations of the different Al forms in all soils decreased in the order Al<sub>p </sub>> Al<sub>o </sub>> Al<sub>cu </sub>> Al<sub>NH4</sub>. Highly stable organo-aluminium complexes (Al<sub>p-cu</sub>) predominated over moderate and low stability complexes (Al<sub>cu</sub>) in all soil plots. The highly stable organo-Al complexes were significantly more abundant in the lower layer, whereas the opposite was observed for the exchangeable Al and the total Al in soil solution. The concentrations of all Al forms (except Al<sub>p-cu</sub>) were significantly and positively correlated with plantation age (Al<sub>o</sub> r = 0.50, p < 0.05 for the upper layer and r = 0.67, p < 0.01 for the lower layer; Al<sub>p</sub> r = 0.64, p < 0.01 for the lower layer; Al<sub>cu </sub>r = 0.84 for the upper layer and r = 0.83 for the lower layer, p < 0.0001; Al<sub>cu-NH4</sub> r = 0.65 for the upper layer and r = 0.78 for the lower layer, p < 0.01; Al<sub>NH4</sub> r = 0.76, p < 0.01 for the upper layer and r = 0.84, p < 0.0001 for the lower layer; total Al in soil solution r = 0.61 for the upper layer and r = 0.60 for the lower layer, p < 0.05). Stepwise linear regression analysis showed that plantation age, pH and total C explained between 67% and 93% of the variance in the Al forms. In all regression models, plantation age was a significant predictor variable for the different Al fractions, except total soluble Al, which is an important variable to consider in the study of chemical properties in forest soils.

Nitrogen fertilizer management on cotton (Gossypium hirsutum L.) yield and quality in two tropical soils

Mulch Application and Plant Spacing Influence on Growth Traits, Pests, Insects and Weeds in Cotton (Gossypium hirsutum L.) Varieties

Agricultural monoculture negatively impacts soil quality, particularly in fragile soils that yield limited crop production and are highly susceptible to degradation. Increasing plant diversity in production systems can be an alternative for maintaining soil ecosystem services and increasing crop yields. This study investigated the influence of increased plant diversity on soil health and its impact on soybean and cotton yield in an Ultisol in the Brazilian savanna in Mato Grosso State, Brazil. Tested five rates of plant diversity after soybean harvest: (1) very low (VL), (2) low, (3) average, (4) long-term average and (5) high (integrated crop–livestock systems (ICLS)) were tested. Plant diversity improves the health of sandy loam soil, increases C and N fractions in particulate organic matter (POM-C and POM-N) and leads to differences in C utilization by the soil microbial community. High ICLS diversity raises total organic carbon content, being POM-C and POM-N, the labile fractions, more efficient to show changes in sandy loam soil, in the short term, over a period of three years. High diversity promoted yield gains of up to 251 % for cotton and 82 % for soybean in relation to VL plant diversity. Changes in soil microbial composition are able to partially explain crop yield in diversified production systems (R2 ranging from 0.51 to 0.80). Diversifying production components is a sustainable way to maintain biological functions and agricultural quality of loam sandy soil in the Brazilian Cerrado in Mato Grosso.

The Southeastern region of the United States (SE-US) is agroecologically diverse, economically agriculture reliant, and distinct from the twentieth-century warming trend. Considering the inextricable link between climate and agricultural production, it is necessary to quantify future environmental implications on economically important crops of cotton ( Gossypium hirsutum L.) and soybean [ Glycine max (L.) Merr.] in the SE-US. The current study used the fixed-effect model (panel data approach) for climate and yield studies, to assess the impact of climatic variables from 1980 to 2020 such as daily maximum temperature (T max ), minimum temperatures (T min ), and rainfall on cotton and soybean yields. The data from 11 states were averaged per growing season and results revealed significant variability in temperature and rainfall during the last four decades. The T max , T min , and rainfall shifted in the range of 0.46–0.50 °C, 1.30–1.45 °C, and 3.74–3.95 cm, respectively, during the cotton growing season (CGS) and soybean growing seasons (SGS). However, the annual rate of change in T max , T min , and rainfall from 1980 to 2020 was in the range of 0.011–0.012 °C, 0.031–0.034 °C, and 0.089–0.094 cm, respectively, during the CGS and SGS. Rainfall had no significant effect on cotton and soybean yields. A 1 °C rise in T min increased cotton yield by 20.8% while decreasing soybean yield by 31.6%. Alternatively, a 1 °C rise in T max decreased cotton and soybean yield by 10.3% and 25.6%, respectively. • The nocturnal temperature explained the overall heating trend for both Soybean and Cotton over the 41-years. • Rainfall had a positive effect on cotton yield but a non-significant negative effect on soybean yield. • The 1 °C incremental T min boosted the cotton yield while reducing the soybean yield. • The 1 °C rise in the T max decreased the cotton yield and reduced the soybean yield.

Mixture of winter cover crops improves soil physical properties under no-tillage system in a subtropical environment

O solo sob plantio direto (PD) sofre alterações ocasionados pela mínima mobilização e pelo tráfego de máquinas. O efeito dessas alterações sobre o desenvolvimento das plantas é dependente das condições climáticas. A escarificação esporádica do solo sob PD tem se apresentado como uma alternativa para minimizar os efeitos da compactação, especificamente em períodos de deficiência hídrica. O objetivo deste trabalho foi avaliar as alterações nas propriedades físico-hídricas de solo sob PD e plantio direto escarificado (PDE) bem como o desempenho da cultura da soja implantada em semeadura direta com dois mecanismos sulcadores na semeadora. O experimento foi instalado em área com seis anos sob PD, sendo que parte da área foi escarificada. Avaliou-se o teor de matéria orgânica, a densidade do solo, a máxima densidade e a densidade relativa, a resistência mecânica do solo à penetração, os componentes de rendimento e rendimento de grãos da cultura da soja. Os resultados indicaram que a escarificação do solo sob PD não afeta o teor de matéria orgânica do solo, diminui a densidade do solo, a densidade máxima, a densidade relativa e a resistência mecânica do solo à penetração. Os componentes de rendimento de grãos da cultura da soja não foram afetados pelos manejos de solo, tampouco pelos mecanismos sulcadores da semeadora. O rendimento de grãos da soja também não foi afetado pelos manejos, mas positivamente pela utilização do sulcador tipo guilhotina em PD.

Phosphorus fractions in Brazilian Cerrado soils as affected by tillage

Corn and soybean yield were assessed across natural gradients of soil salinity in sandy loam and silty clay loam soils in the Northern Great Plains. Corn and soybean seeded to sandy loam soil demonstrated significant yield declines, with salinity tolerance indices of 9.68 and 7.04, respectively. Corn and soybean seeded to silty clay loam soil demonstrated no significant yield declines. Results demonstrate that corn and soybean yields respond differently to salinity in different textures. Soil salinization is a global issue affecting 831 million ha of arable land and resulting in approximately US$27.3 billion in crop losses annually. The purpose of our research was to determine the effects of natural gradients in soil salinity on field‐grown corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] in silty clay loam and sandy loam soils in southeastern North Dakota. Both corn and soybean yield were hand‐harvested at the ends of the 2014 and 2015 growing seasons and related to the electrical conductivity (ECe) of the root zone using the modified discount response function (MDRF). Neither corn nor soybean yields demonstrated significant declines when grown in finer‐textured soil. Contrarily, when corn and soybean were grown in sandy loam soils, significant declines occurred. Calculated values at which 50% yield reductions occurred (EC50) in sandy loam soil resulted in salinity tolerance indices (STI) of 9.68 for corn and 7.04 for soybean. The lack of yield declines for both crops in silty clay loam soil may indicate a reduced effect of salinity stress in finer textures. Additionally, the composition of ions in the soil solution may also play a role in crop response to salinity.

No-till system (NTS) occupies 20 million hectares with grain crops in Brazil. However, calcium deficiency and aluminum toxicity can limit crop yields in many soils, and liming, associated to gypsum application, is an option for improving soil management. The objective of this study was to evaluate the effects of lime and gypsum application on the composition of soil water extracts of a clayey Rhodic Hapludox, cultivated with soybean under NTS. The experiment had a randomized complete block design with split-plots. The plots consisted of lime treatments (either a single rate of 4.5 t ha−1 or three annual rates of 1.5 t ha−1) surface-applied or incorporated at 0.2 m depth. The subplots received surface applications of gypsum (3, 6 and 9 t ha−1). Liming increased total calcium and magnesium concentrations and the magnesium free Form activity (aMg2+) in the water extracts. The effect of liming on Mg was observed at deeper layers of the soil profile. Gypsum increased total concentration and free forms activities at calcium (aCa2+) and sulfate, but decreased to magnesium in the 0.05–0.2 m soil layer. Part of Mg lost from these upper layers probably contributed to increased Mg in the subsoil (0.4–0.8 m). Free forms activities at the aluminum, calcium, magnesium and sulfate were lower than the total concentrations, mainly for aluminum. Ca and Mg concentrations in soybean leaf tissue were positively correlated to the aCa2+ and aMg2+ in the soil water extract. Soybean grain yield was negatively correlated to both Mn total concentration and activity (free form) in the soil water extract, but it was positively correlated to sulfate (total concentration and free form activity) in the subsoil layer and to the Ca total concentration in the upper layer (0–0.05 m). It is concluded that lime and gypsum ameliorate soybean grain yield under NTS.

Survival of entomopathogenic nematodes (EPNs) in soils is attributed to their entering a dormant state—anhydrobiosis—as soil moisture decreases, but EPNs with poor desiccation tolerance and low anhydrobiotic capabilities may practice desiccation avoidance. We compared the effect of soil moisture gradient on downward movement of the highly desiccation-tolerant Steinernema carpocapsae and the poorly desiccation-tolerant Heterorhabditis bacteriophora. Infective juveniles (IJs) were applied to the surface of moist (11–13% w/w moisture) sandy soil in buckets. Nematode distribution was monitored at different depths 3, 14 and 28 days after application. In uncovered buckets, soil moisture decreased to 1% in the upper 5-cm layer after 28 days. H. bacteriophora IJs abandoned the upper soil layers as dryness intensified with >80% found in the bottom (20–25 cm) layer. In contrast, >70% S. carpocapsae IJs remained in the upper layer. In covered buckets, with 10% moisture throughout the experiment, heterorhabditid IJs were equally distributed between the 10–15 cm and 20–25 cm layers; only 7% remained in the upper layer. Again, >70% S. carpocapsae IJs remained in the upper layer throughout. Soil type influenced H. bacteriophora IJs' downward migration. In sandy and sandy loam soils, with rapid evaporation, >80% IJs were in the bottom layer 14 and 28 days after application. In the loam soil, with higher moisture retention, >75% IJs remained in the 10–15 cm layer and <20% migrated to the bottom. Results provide initial evidence of a possible stress-avoidance strategy in H. bacteriophora under natural conditions.

Although the movement of liming materials under no-tillage (NT) systems can intensify stratification of soil chemical properties and be deleterious to soybean growth, little is known regarding the soil acidity indicators used to predict lime requirement (LR) in Brazilian soils under NT. Thus, we hypothesize that the recommendation criteria used for predicting LR in soils under NT must be different from those adopted in soils under conventional tillage (CT), and the reference values for such liming indicators may vary according to the phase following the adoption of the NT system. The study aimed to obtain soil acidity indicators for soybean (Glycine max (L.) Merill) in tropical acid soils under no-tillage (NT) systems and their respective critical levels according to the phase of NT. Sites under NT were commercial soybean crop areas located in the Cerrado region, Brazil. Systems analyzed were NTI (NT management from 0 to 5 years&amp;mdash;initial phase), and NTTC (NT management from 5 to 20 years&amp;mdash;transition-consolidation phase). Soil samples were collected at the 0-5, 0-10, and 0-20 cm layers, and analyzed for chemical characteristics. Relationships between crop yield response of soybean to lime application and various soil acidity-related characteristics led to establishing soil acidiy indicators for liming in tropical acid soils under no tillage. Critical levels were approximately similar in both phases of NT for exchangeable Ca and Mg, and potential acidity, but varied greatly depending on the soil layer and phase of NT management for soil pHCaCl2, CECpH7.0, and base saturation. In general, for both phases of NT, the critical levels of soil acidity indicators were lowest for the 0-20 cm layer, moderate for the 0-10 cm layer, and highest for the 0-5 cm layer. Lime applied with incorporation in the NTTC phase kept the soil with chemical attributes more favorable for plant growth than when surface liming was employed in the NTI phase, which was verified by the soybean yield response. Our results indicate the differences on the soil acidity indexes between the top and bottom depths that would not have been realized in a soil sampling for conventional tillage. Hence, recommendation criteria for lime application considering distinct soil depths and NT systems will be helpful when making lime decisions. Further research should focus on the development of reliable methods for predicting LR according to the NT phase and consequently maximize soybean production under NT systems in Brazil.

A field experiment was conducted in 2007, 2008, and 2009 in central Alabama to evaluate the effects of cover crop mechanical termination, strip tillage width, and row cleaners attached either to the tillage implement or planting units, on cotton population and yield. Treatments included roller (present or absent), in-row subsoiler (wide and narrow strips), and row-cleaners attached either to subsoiler, planter, or both. Rye was terminated with glyphosate (both rolled and non-rolled rye) in mid-April, and tillage treatments were applied; cotton was planted three weeks after tillage. In 2007, generally higher cotton stands were associated with rolled rye residue (137,134 plants/ha) vs. non-rolled rye (115,641 plants/ha). On average, significantly higher cotton seed yield was found for rolled rye (4,540 kg/ha compared to non-rolled rye (4,332 kg/ha). Examining specific treatments, the highest cotton seed yield (4,933 kg/ha) was associated with rolled rye under narrow strip tillage with row cleaners attached to both subsoiler and planter. The lowest cotton yield (3,913 kg/ha) was associated with non-rolled residue, under narrow strip tillage with row cleaners present on both subsoiler and planter. In 2008, no difference was found in cotton stand for rolled (108,375 plants/ha) and non-rolled rye (107,719 plants/ha). Cotton seed yield was higher in 2008 than in 2007 due to a severe drought in Alabama during 2007. In 2008, slightly higher cotton yield was reported for non-rolled rye (5,658 kg/ha) vs. rolled rye (5,419 kg/ha). The non-rolled rye, narrow strip subsoiling, and row cleaners on subsoiler generated the highest cotton yield (5,812 kg/ha) compared with the lowest (5,171 kg/ha) by rolled rye, narrow strip, and row cleaners on the planter. In 2009, cotton stand for rolled rye was higher (115,036 plants/ha) compared to non-rolled rye residue (65,894 plants/ha). In 2009, the cotton yield was substantially reduced by flooding of the experimental area. Because of the excess water, the cotton yield was lower (2,672 kg/ha) compared to 2007 and 2008 growing seasons. Soil strength measurements taken in fall 2009 showed significantly lower cone index values with rolled vs. non-rolled rye from 0 to 15-cm depth, with trends reversed after

Context No-tillage (NT) has been gaining popularity over the conventional tillage (CT) for agricultural sustainability. Field experiments conducted worldwide to compare crop production under NT vs CT systems are generally site specific and expensive to maintain over longer duration. To overcome this gap, process-based models have been used to simulate the potential impact and benefits of various management practices on crop yield and soil properties under different environmental conditions. Aims (1) We evaluated the Cropping System Model (CSM)-CERES-Maize and CSM-CROPGRO-Soybean model for NT and CT systems; and (2) compared the long-term impacts of NT and CT on crop yield and soil organic carbon (SOC). Methods Two crop models, available in the Decision Support System for Agrotechnology Transfer (DSSAT), were calibrated and evaluated using maize (Zea mays L.) and soybean (Glycine max L.) yield data from 2006 through 2011 under CT and NT treatments. Key results For crop yield, we showed that the coefficient of determination (R2) for the calibration and evaluation phases of CERES-Maize model were 0.94 and 0.94, respectively, while the index of agreement (d) for these phases were 0.93 and 0.86. Similarly, the R2 values for the calibration and evaluation phases of CROPGRO-Soybean model were 1.00 and 0.65, respectively, with d-values of 0.99 and 0.85. Conclusions The results from these long-term (30-year) simulations suggest that compared to CT, the NT system enhanced SOC over time and, hence, crop yield and biomass production. Implications Application of NT can be beneficial for enhancing the soils and crop production in the long-term as compared to the CT system.

Concern over soil erosion and high production costs in conventional tillage systems has led to interest in reduced tillage systems for navy bean (Phaseolus vulgaris L.). Research was conducted for 2 yr at two sites with different soil textures to develop weed management strategies in reduced tillage systems for navy bean. Twelve weed management strategies were evaluated in conventional tillage, no-till, and zone-till systems in 1995 and 1996 in Michigan. Weed management strategies included hand-weeding, cultivation-only, preemergence herbicides, preemergence followed by postemergence herbicides, and postemergence herbicide treatments. Glyphosate was applied to control existing vegetation in the no-till and zone-till systems. Redroot pigweed (Amaranthus retroflexus L.) and common lambsquarters (Chenopodium album L.) populations were lower in the no-till and zone-till systems than in the moldboard plow and chisel plow systems. Imazethapyr plus pendimethalin preemergence provided less weed control than preemergence followed by postemergence and total postemergence treatments in two of four site years. Preemergence followed by postemergence herbicides controlled annual broadleaf weeds better than postemergence herbicides alone. Navy bean seed yield at the sandy clay loam site was 50% higher in moldboard plow and chisel plow tillage systems than in the no-tillage system. The highest average gross margin was in the chisel plow system. There was no difference in navy bean seed yield due to tillage system at the sandy loam site and the no-tillage and zone-tillage systems had the highest gross margins. These data suggest that weeds can be controlled in reduced tillage systems and the success of reduced tillage systems in dry bean production varies by soil texture.