Pablo Undurraga

The objective of this study was to evaluate the effect of four cycles of six biannual rotations and four levels of incorporation of residues for each crop on the chemical properties of a volcanic soil from central-southern Chile. Methods: After six biannual rotations (canola–bread wheat, bean–bread wheat, canola–durum wheat, bean–durum wheat, canola–corn, and bean–corn) and four levels of residue incorporation (0, 50, 100, and 200%), we evaluated the chemical properties of a volcanic soil through eight years of cultivation. Results: The chemical properties of the soil were affected mainly by crop rotation and to less extent by the dose of residue incorporated. Beans showed a positive relation with soil pH, unlike canola with a negative effect (p < 0.05). Corn was also noticeably negative for available P. The application of increasing doses of residue positively affected the exchangeable K and Mg (p < 0.01). There were also positive correlations between pH and exchangeable Ca, exchangeable Ca and Mg, and available S and exchangeable Al and negative correlations between pH and exchangeable Al, pH and available S, and available S with exchangeable Ca and Mg. Conclusions: Carrying out different crop rotations seems to be a boost for chemical properties of the soil, while the incorporation of residues allows higher concentrations of exchangeable K and Mg.

Conservation practices in agriculture using crop rotations and residue management benefit the productivity; these can vary depending on climate and soil conditions, crops, and amount of incorporated residue. The present study evaluated the effect of two biannual rotations; canola (Brassica napus L.) – corn (Zea mays L.) and bean (Phaseolus vulgaris L.) – corn rotations with four residue incorporation rates (0%, 50%, 100%, and 200%) of the preceding crop on corn grain yield, residue production, and nutrient concentration and extraction after two rotation cycles in a volcanic soil of moderate depth in south-central Chile. Grain yield varied between 17.04 and 17.40 Mg/ha, residue production between 16.41 and 16.50 Mg/ha. The preceding crop affected concentration and extraction of some nutrients in both grain and residue. The residue rate affected both concentration and extraction of some nutrients only in the grain. The Ca distribution to the corn grain was negatively affected by both the preceding bean crop and increasing residue incorporation rate. The ranking of total macronutrient extraction in the corn crop was K > N > Ca > P > Mg > S. The extraction means ranged from 320 to 326, 56.0 to 57.1, 365 to 374, 86.5 to 99.3, 39.4 to 42.4, and 22.6 to 23.7 kg/ha, whereas grain nutrient distribution coefficients ranged from 64.5 to 66.8, 90.1 to 90.9, 23.1 to 23.7, 1.3 to 2.0, 50.8 to 57.5, and 60.3 to 60.6 for N, P, K, Ca, Mg and S, respectively.

Background: There are few reports of crop rotations with high residue incorporation in terms of their effects on indicator crop yields and soil properties, so this study evaluated the effect of two medium-term biannual rotations on wheat yield development and soil chemical properties after six years of rotation. Methods: The experiment was conducted with two biannual rotations (canola–wheat and bean–wheat) and four residue incorporation levels (0%, 50%, 100%, and 200%) in an Andisol in south central Chile. Wheat grain yield and residue production were evaluated during each biannual cycle during three cycles of crop rotation, and soil chemical properties were evaluated at final evaluation. Results: The use of beans as a wheat preculture partially improved grain yield in 7.3%. The chemical properties of the soil showed an increase in pH (0.08 units), organic matter content (15 g kg⁻¹), and concentrations of P (2.8 mg kg⁻¹), S (7.4 mg kg⁻¹), and Al (0.03 cmol₊ kg⁻¹) after canola cultivation, while after bean cultivation there was an increase in the available N concentration (3.7 mg kg⁻¹). The use of increasing doses of residue allowed for an increase in the soil pH and decrease in the exchangeable Al concentration. Conclusion: The continuous incorporation of the residues produced within the biannual rotations evaluated in this volcanic soil did contribute to improving some chemical properties of the soil without affecting wheat crop yield.

Mulch is widely used in blueberry cultivation for weed control; however, there is still uncertainty as to how the use of different types of mulch alters leaf photosynthetic behavior and the quality and productivity of blueberry fruit. The objective of our research was to evaluate the effect of different types of mulch on the physiological, quality and yield characteristics of blueberries. Three treatments were established: T1 (control), T2 (pine bark) and T3 (geotextile) in two cultivars: Ochlockonee and Legacy. The parameters measured were: the photochemical quantum yield of photosystem II (Y_II), the maximum photochemical efficiency of photosystem II (F_v/F_m), electron transport rate (ETR), fruit quality and yield parameters. The results show lower soil temperature in T1 during the morning (p < 0.05) compared to the two mulch treatments, which was the opposite during the afternoon, the temperatures were more stable and closer to the optimum (21 °C) in T2 and T3, with mulch favoring root and foliar development. On the other hand, the treatments with mulch favored a higher photosynthetic efficiency of photosystem II (Y_II) at the end of afternoon and were associated with an increased firmness of the fruit; the firmness of all fruits was higher than that in the control treatment (p < 0.05) in the Legacy cultivar, but without differences between them, with values of 73 and 75 gf mm⁻¹ for T2 and T3, respectively, and 67 gf mm⁻¹ for the Control. In addition, it was observed that the use of mulch only increased the fruit yield in the Legacy cultivar, both in T2 and T3, with both being superior to T1 (p < 0.05). It can be concluded that the use of mulch decreases soil temperature in the midday and late afternoon, improving the edaphoclimatic conditions during the development of the blueberry. In addition, plants with mulch have lower stomatal conductance, which promotes greater photosynthetic efficiency during the day, increasing both firmness and fruit yield.

Conservation agriculture with use of crop rotations and residue management provides many benefits to the soil and environment, which vary depending on climatic and soil conditions, crops between of the rotation, and the amount of incorporated residue. The present study evaluated the effect of two medium-term of canola (Brassica napus L.)-wheat (Triticum aestivum L.) and bean (Phaseolus vulgaris L.)-wheat rotations with four residue incorporation rates of preceding crop (0, 50, 100, and 200%) on wheat grain yield and nutrient concentrations; Nitrogen (N), Phosphorous (P), Potassium (K), Calcium (Ca), Magnesium (Mg) and Sulfur (S) at the end of the fourth season in a volcanic soil in south-central Chile. Grain yield varied between 5.77 and 5.96 Mg ha⁻¹ and was not affected by the preceding crop. The residue incorporation rates had no effect on the evaluated parameters. The preceding crop affected grain K and Mg concentration, which increased after bean. The Ca concentration in the residue was positively affected by the canola crop. Total macronutrient extraction in the wheat crop was 444.1 kg ha⁻¹. The ranking of total macronutrient extraction in the wheat crop was N > K > P > Ca > S > Mg with means of 198–221, 26.1–30.6, 133–163, 20.8–27.1, 13.4–16.5, and 14.9–16.5 kg ha⁻¹, respectively.

Soil acidity is one of the main factors that reduces productivity in agricultural crops, and it is corrected with materials that neutralize acidification. Among soils affected by acidity are those of volcanic origin. At least 30 % of agricultural soils in Chile are of volcanic origin, and acidity correction practices must be constantly performed. This study aimed to evaluate the effectively of two materials that may neutralize soil acidification and increase yield production in Chilean volcanic soils. An experiment [...] ABSTRACT Soil acidity is one of the main factors that reduces productivity in agricultural crops, and it is corrected with materials that neutralize acidification. Among soils affected by acidity are those of volcanic origin. At least 30 % of agricultural soils in Chile are of volcanic origin, and acidity correction practices must be constantly performed. This study aimed to evaluate the effectively of two materials that may neutralize soil acidification and increase yield production in Chilean volcanic soils. An experiment

Crop rotations and residue management contributes to the sustainability of the soil and environment and reduction of fertiliser use. However, appropriate crop and residue level combinations have yet to be determined to maximise productivity, while ensuring the preservation of soil resources in different agricultural production systems. The experiment evaluated production and soil chemical properties in bean after three preceding crops (bread wheat, durum wheat, and corn) with four residue incorporation levels (0%, 50%, 100%, and 200%) under irrigation conditions in volcanic soil in south central Chile. A split plot design with four replicates was used. Results indicated that the production of grain and crop residue of bean were higher after corn and durum wheat. The preceding crop also affected some soil chemical properties, especially after the corn crop. The production parameters were not affected by the different residue levels; these had a positive effect on the concentrations of N, K, and Mg and an effect that was directly proportional to the residue level being used. Correlations between soil chemical properties were also established, consistently highlighting the increase in the concentration of the nutrients N, K, Ca, and Mg associated with increases in organic matter content.

The intensive use of agricultural soils reveals the massive application of agrochemicals. There is no follow-up of the presence of pesticide residues in soil or their toxic effects on organisms that are beneficial for agrosystems, such as earthworms (Lumbricus terrestris L.) The objective of this study was to evaluate the effect of pesticides used in horticultural orchards on earthworms, and the use of earthworms as an indicator through carboxylesterase (CbE) activity, which is an enzyme involved in the detoxification metabolism of organophosphorus, carbamates, and pyrethroids. Eight individuals were place in each polyethylene container and the container were buried under the soil surface in two apple orchards, one under organic management and the other under conventional management. The experiment was carried out in triplicate. A control treatment was conducted in the laboratory. The experiment was repeated in autumn, winter, spring, and summer of the 2014-2015 study period. Three internal gut tissues of the earthworm were measured for CbE activity in the laboratory. Results showed higher CbE activity in the crop-gizzard of the control treatment with 14.22 ± 1.00 μmol min-1 mg-1 in winter; the lowest activity was recorded in soil under conventional management in summer with 6.15 ± 2.77 μmol min-1 mg-1 (p ≤ 0.05). There was a seasonal difference in enzymatic activity that was higher in winter and autumn with 14.22 and 13.93 μmol min-1 mg-1, respectively, and lower in summer and spring with 6.15 and 6.31 μmol min-1 mg-1 (p ≤ 0.05), respectively; enzymatic activity was associated with higher pesticide application. It can be concluded that CbE activity is sensitive to the inhibitory action of pesticides and can therefore be used as a biological indicator of agrochemicals.

Soil organic matter (OM) content is a quality indicator, but is an inadequate indicator in the short-term because these changes take place slowly, so dissolved organic components have emerged as an alternative. In volcanic soil subjected to different crop rotations with distinct land use intensity, dissolved organic C and N (DOC and DON) were determined as well as their relationship with total C and N contents in the soil, considering the effects of crop rotation, fertilization level, and soil depth. In humid samples of Humic Haploxerands collected at four depths up to 40 cm, DOC and DON contents were determined by extraction with K2SO4 and filtered. Results indicated interaction between the studied factors, DOC fluctuated between 67.8 and 151.7 mg kg-1 with the highest value with intensive management in rotations that included corn (Zea mays L.) associated with a higher fertilization. DON fluctuated between 4.62 and 37.4 mg kg-1 with the highest value in non-intensive rotations that included prairie. With respect to total C, DOC reached 0.40% with intensive management and the lowest value in non-intensive management. DON showed values between 0.13 and 0.68% with respect to total N with intensive and non-intensive management, respectively. Tillage management affected DOC and DON contents depending on the fertilization level and the depth at which it was determined, and were also affected by the crop included in the rotation, thus making these parameters good indicators to evaluate the effects of agronomic management in the short-term.