Abstract
Abstract A high proportion of the soils in the central zone of Santa Cruz, eastern Bolivia, are chemically and physically degraded, with low organic matter and N contents, compacted subsoil layers and a propensity to crusting, hardsetting and wind erosion. The aim of the experiment discussed in this paper was to identify suitable cover crops to be used in combination with subsoiling for the rehabilitation of degraded soils and the improvement of crop yields in eastern Bolivia. Fertilizers were not used because of their high cost. An experiment with a split complete block design, with subsoiling and no‐subsoiling as the main treatments, 14 cover crops and a continuously cultivated soybean/wheat control as the subtreatments, and four replications, was established on a degraded site comprising a mosaic of two compacted siliceous isohyperthermic soils (a coarse loamy Typic Ustropept and a fine loamy Typic Haplustalf). After a two‐year fallow period, the cover crops were incorporated and test crops were sown for five seasons to evaluate the effects of the treatments on subsequent crop yields. Soil samples were taken to measure changes in chemical fertility. The only significant cover crop effect on soil nutrients was an increase in exchangeable K from 0.47 to 0.56 cmol c kg −1 by Lablab; subsoiling had no effect on chemical fertility. For all treatments there was an average 24 per cent increase in soil organic matter from 13.1 g kg −1 at 3 months after cover crop incorporation to 16.3 g kg −1 at 19 months after incorporation. No significant differences in total N were found during this period. Test crop yields were not influenced by subsoiling, but were significantly increased by some of the cover crops as compared to the soybean/wheat control during the first three seasons only. Evidence from foliar analysis suggests that the effects of the cover crops on soybean yields were not nutritional and so presumably were physical in nature, whereas the benefits on wheat yields were possibly related to increased N availability. Panicum maximum var. Centenario and P. maximum var. Tobiatá gave the highest total yield increases over the first three cropping seasons (101 and 85 per cent, respectively), but these yield increases would not compensate the farmer for the loss of four crop harvests whilst the land was in fallow. These results highlight the difficulties of rehabilitating soil fertility and increasing crop yields through the use of subsoiling and cover crop fallows on compacted, low organic matter soils in eastern Bolivia.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 11
Claim · model-written summary
Lablab increased exchangeable soil K from 0.47 to 0.56 cmol c kg −1.
- Taxon
- soybean/wheat
Glycine max
Triticum aestivume1 - Treatment
- Lablabe0
- Outcome
- exchangeable Ke0
- Direction
- increasee0
- Value
- 0.47 to 0.56 cmol c kg −1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The only significant cover crop effect on soil nutrients was an increase in exchangeable K from 0.47 to 0.56 cmol c kg −1 by Lablab;”
e1“continuously cultivated soybean/wheat control”
Claim · model-written summary
Subsoiling did not affect soil chemical fertility.
- Taxon
- soybean/wheatGlycine maxTriticum aestivume1
- Treatment
- subsoilinge0
- Outcome
- chemical fertilitye0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“subsoiling had no effect on chemical fertility.”
e1“continuously cultivated soybean/wheat control”
Claim · model-written summary
Soil organic matter increased by an average 24 per cent after cover crop incorporation.
- Taxon
- soybean/wheatGlycine maxTriticum aestivume1
- Outcome
- soil organic mattere0
- Direction
- increasee0
- Value
- 24 per cente0
- Qualifier
- at 19 months after incorporatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For all treatments there was an average 24 per cent increase in soil organic matter from 13.1 g kg −1 at 3 months after cover crop incorporation to 16.3 g kg −1 at 19 months after incorporation.”
e1“continuously cultivated soybean/wheat control”
Claim · model-written summary
Total soil N did not differ significantly over the post-incorporation period.
- Taxon
- soybean/wheatGlycine maxTriticum aestivume1
- Outcome
- total Ne0
- Direction
- No significant differencese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No significant differences in total N were found during this period.”
e1“continuously cultivated soybean/wheat control”
Claim · model-written summary
Subsoiling did not influence test crop yields.
- Taxon
- soybean/wheatGlycine maxTriticum aestivume1
- Treatment
- subsoilinge0
- Outcome
- Test crop yieldse0
- Direction
- not influencede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Test crop yields were not influenced by subsoiling”
e1“continuously cultivated soybean/wheat control”
Claim · model-written summary
Some cover crops increased test crop yields over the soybean/wheat control during only the first three seasons.
- Taxon
- soybean/wheatGlycine maxTriticum aestivume0
- Treatment
- some of the cover cropse0
- Outcome
- soybean/wheate0
- Direction
- increasede0
- Qualifier
- during the first three seasons onlye0
- Comparator
- soybean/wheat controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were significantly increased by some of the cover crops as compared to the soybean/wheat control during the first three seasons only.”
Claim · model-written summary
Foliar analysis suggested that cover crop effects on soybean yield were physical rather than nutritional.
- Taxon
- soybeanGlycine maxe0
- Treatment
- cover cropse0
- Outcome
- soybean yieldse0
- Qualifier
- physical in naturee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Evidence from foliar analysis suggests that the effects of the cover crops on soybean yields were not nutritional and so presumably were physical in nature”
Claim · model-written summary
The authors suggested that cover crop benefits for wheat yields may involve increased nitrogen availability.
- Taxon
- wheatTriticum aestivume0
- Outcome
- wheat yieldse0
- Qualifier
- increased N availabilitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the benefits on wheat yields were possibly related to increased N availability.”
Claim · model-written summary
Panicum maximum var. Centenario gave a 101 per cent total yield increase over the first three cropping seasons.
- Taxon
- soybean/wheatGlycine maxTriticum aestivume1
- Treatment
- Panicum maximum var. Centenarioe0
- Outcome
- total yielde0
- Direction
- increasese0
- Value
- 101e0
- Qualifier
- over the first three cropping seasonse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Panicum maximum var. Centenario and P. maximum var. Tobiatá gave the highest total yield increases over the first three cropping seasons (101 and 85 per cent, respectively)”
e1“continuously cultivated soybean/wheat control”
Claim · model-written summary
P. maximum var. Tobiatá gave an 85 per cent total yield increase over the first three cropping seasons.
- Taxon
- soybean/wheatGlycine maxTriticum aestivume1
- Treatment
- P. maximum var. Tobiatáe0
- Outcome
- total yielde0
- Direction
- increasese0
- Value
- 85 per cente0
- Qualifier
- over the first three cropping seasonse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Panicum maximum var. Centenario and P. maximum var. Tobiatá gave the highest total yield increases over the first three cropping seasons (101 and 85 per cent, respectively)”
e1“continuously cultivated soybean/wheat control”
Claim · model-written summary
The yield gains would not compensate farmers for four lost harvests during fallow.
- Taxon
- soybean/wheatGlycine maxTriticum aestivume1
- Outcome
- yield increasese0
- Value
- four crop harvestse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these yield increases would not compensate the farmer for the loss of four crop harvests whilst the land was in fallow.”
e1“continuously cultivated soybean/wheat control”
The same questions in other papers
Megathyrsus maximus · yield · Glycine max (soybean)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- positive
cover crop · organism · Triticum aestivum (wheat)Positive and negative results
4 papers in the same direction as this paper · 1 in the opposite direction · 2 reporting no difference from an alternative
- no effect
- no effect
- no effect
4 papers more in this group
See all 8 papers →cover crop · organism · Glycine max (soybean)Positive and negative results
3 papers in the same direction as this paper · 7 in the opposite direction
- no effect
- no effect
- negative
7 papers more in this group
See all 11 papers →tillage · yield · Glycine max (soybean)Positive and negative results
125 papers in the same direction as this paper · 264 in the opposite direction
- positive
- positive
- positive
386 papers more in this group
See all 390 papers →tillage · yield · Triticum aestivum (wheat)Positive and negative results
297 papers in the same direction as this paper · 1,116 in the opposite direction
- positive
- positive
- positive
1,410 papers more in this group
See all 1,414 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.